Sure thing. What is the objective definition of the term "a full game" that you used in your alternative headline? Does Assetto Corsa Competizione meet that definition and if so, why does GT Sport not?
Sure thing. However how you're choosing to define things is... a choice. It isn't objective, and thus is not a fact - and we can examine the rationale behind your choice.
In GT Sport there are 83 different places you can go and drive a car and set a recorded lap time (there is an 84th, but it has no defined layout, and only appears in one place; players cannot select it as a course). I don't really know what better terminology there is than "a track" for "place you can drive a car and set a recorded lap time". Circuit also works, but has the same essential connotations. Course also works, again with the same basic meaning.
These places are at 29 different named locations (I don't know where you're getting 31 from). But a location is just a broad geographical (whether fictional or not) brush. Let's look at Willow Springs as an example. That's a place/location. There's three different tracks on it (two of which the game allows you to drive in reverse) - and they are completely different. Three different groups of people can drive on all three simultaneously without ever interfering with any other group.
By the argument that GT Sport has 29 tracks (again, you say 31 but the fact is that there's 29 track locations), Big Willow, Streets of Willow, and Horse Thief Mile are one track. But we've established that there's three completely unconnected circuits here that you can drive on all at the same time. That would make three tracks.
Here's where "layout" - the term GT Sport uses - falls flat. GT Sport says there's five layouts, but really there's only three - the fact that you can drive the other way around two of the tracks does not actually change how the tracks are laid out. Everything is in the same place; the layout is no different. But you can drive, and set a lap time, on these two additional versions.
Then there's places like Kyoto and the Nurburgring. Each has two circuits that are completely unconnected; two groups can drive both tracks simultaneously without ever meeting. However, each also has a unified layout, with new crossover sections of track that are not part of either of the other circuits - these sections of road surface are unique to that course, but you cannot drive on the 24hr version of the Nurburgring without also driving on sections of the other two tracks.
The "location = track" argument says that Nurburgring GP and Nurburgring Nordschleife are one track, despite sharing no section of road surface, while the "place you can record a lap time = track" argument says that they are two - and the 24hr track is a third.
Let's move to Tokyo. These six tracks look pretty obvious. It's three completely different bits of road, which you drive in opposite (Outer, Inner) directions. Except it isn't; the bulk of each of the three is the same, but the slip roads (or on/off-ramps) are different. Moreover, South Outer skips out an entire section of track that South Inner uses, as well as using different slip roads. The section from the start line to the pits of Outer is broadly the same as the section from the pits to the finish line of Inner (there's a different access road between the pits and the esses), but otherwise they use different sections of road throughout.
Of course there are tracks where the bulk of the course is shared between two different layouts - Brands Hatch, Red Bull Ring, Blue Moon Bay, Suzuka, Autopolis, Sardegna - and others where there's literally just a corner or two that is different - Fuji, Monza, La Sarthe.
Ultimately GT Sport has the following breakdown:
29 geographical locations (12 post-launch)
37 completely separate individual circuits (15 post-launch)
83 different courses for which it is possible to record a lap time (44 post-launch)
84 places to drive (44 post-launch)
The argument that "it has 31 tracks" (sic) requires you to classify a rally track and three road courses as one track, and three wholly separate road courses as one track, because they are in the same geographical location (Sardegna, Willow Springs respectively). The argument that it has 83 tracks only requires you to classify somewhere you can record a lap time as a track.
If that's your choice, that's your choice. It seems like an extremely arbitrary distinction to make, and not one borne out by facts.
For a nice, fun note, the article doesn't contain any mention of the 83/84 figure. In fact it only mentions the locations and number of post-launch courses. My headline also contains no numbers at all...
What people care about driving is opinion, not fact. However the facts you have stated there don't add up at all.
Exactly what constitutes a "concept car" is up to you, but even if you limit it exclusively to Vision GT cars only there's 44 - you can cut that to 29, I think, if you exclude all variations (such as Gr.1 and Gr.X Hyundai VGTs, the four SRT Tomahawks, the three AMGs, and so on). Of course the Audi e-tron Vision GT and Bugatti Vision GT are both also actual real cars, but there's a fictional version of both in Gr.X too, so we can keep them in the list.
Aside from those, there's a load of other concept cars. Take the Abarth BAT1, a concept car shown in 1952, or the Plymouth XNR concept from 1960. More recently there's the GR Supra Racing Concept from last year, and we can't forget the Mazda that arrived this week - a 2015 concept car developed into a GT-exclusive model. That would also ask why we've not included the Citroen GT by Citroen, which had a similar genesis (and was almost a real car), on the concept car list - and its two race car variants.
That would then also ask questions about other GT-exclusive race cars that are not present in the real world. Have a look at the Beetle Gr.3, or the Atenza Gr.4 and Gr.3 (the Gr.4 actually has a real-world inspiration, but as that car was diesel and not 4WD, sits on the made-for-GT bench), or the mid-engined RCZ Gr.3, or its Road Car alternative, and the other six Gr.3/Gr.B road cars.
There's a lot of cars you could class as concept cars in GT Sport, but the only way to get a number as low as the one you stated you'd have to exclude everything but the first instance of a Vision GT car - and that number is lower (but should be higher at year-end; there's two more coming).
As for 20 pick-up trucks and 4x4s... there's two, and they're both pick-up trucks (F150 Raptor, Tundra TRD Pro). There weren't even 20 in GT6.
I'm glad you are happy and feel you got value for money, but let's not go down that road, because some ridiculous comparisons can arise. 
