As a beginner (<300 total hours in Gran Turismo, lifetime; it is easy for me to get bronze in an online time time trial but hard for me to get silver, and I have never gotten gold) and as a busy person, I am happy that the “daily” races change weekly. I learned I have to spend about 2 hours in a new race just in qualifying, to be able to race without being a total menace. Further, each separate session I need to practice in qualifying for 30 minutes to re-gain any semblance of form. Spending 5 hours per week in the game would be a LOT and that would be just two sessions per week for me. So, one different race + a new time trial per week is plenty for me.
Based on the fact that I have some trophies in the game that only like 15% of players get, I extrapolate that the vast majority of people who purchase GT play even fewer total hours than I have, and fewer hours per week, and probably only a couple of sessions or less each week.
Image you can only play two hours per week, one hour at a time, but you are way better than me. Then you spend 15 minutes qualifying and 45 minutes racing, twice a week. That is only 6 total races per week, or less. This is probably the vast majority of people.
That, plus the need to ensure there are enough people with similar DR+SR available, explains why there isn’t more variety. (After midnight US Pacific time, I find race A might only have 8 people in a race.) Not just cost-cutting like suggested in the video.
I guess it also partly explains why penalties are not stricter and why the rolling starts and ghosting are used to reduce lap one turn one incidents. The vast majority of people just don’t have time to become good enough to consistently have a clean grid start + turn one. That said, I do think it makes a lot of sense to make this a function of DR. But, I guess a very slim minority of drivers have a high DR, so it is probably difficult for them to invest too much into catering to them.