I used to work at a large movie theatre chain as an usher and then as a treasurer / manager, so I know a bit about why things cost what they do.
When I started, a ticket cost $10 (Canadian). The money from ticket sales is not profit; it goes towards operating the theatre, and bidding on films (not sure about any other country, but in Canada there's a law that regulates how much distance must exist between two movie theatres showing the same movie, so since they're all pretty much built close to each other to compete, only one of the two theatres in my neighbourhood plays a movie; it's never at two theatres at the same time). However, I noticed that while I worked there, the price of tickets kept going up .25 cents at a time about twice a year. I assume this was because AMC appeared in Canada and began stealing customers and their money away from the chain I worked for.
The profit all comes from the food, and that's why the mark-up is so staggering. They don't allow you to bring your own food, and they know most people like to eat and / or drink something while watching a movie, so they've basically got a license to print money; they can charge pretty much whatever they want for popcorn, soda, and candy, as long as it's within reason, or else people won't buy it.
I also heard another justification for prices at movie theatres. Going to see a movie is basically a night's entertainment, similar to going out for dinner, to a comedy club, to a dance club, a bar, a baseball game, etc. So when you compare prices movies are actually cheaper, even when you factor in the price of candy, and buying candy is OPTIONAL!
Why not eat before seeing the movie? Or if you're less scrupulous, buy some candy at a supermarket or a drugstore and sneak it in. As for popcorn, if you must have it, you'll probably have to buy it since it's pretty hard to smuggle in without a backpack or a large coat, and you've got to prepare it at home and then it's no longer warm and fresh.
Anyway, the theatre I worked at got its ticket prices all the way to about $14 last year, and I guess they took a look at their books and decided they should drop those prices to bring people back. Now prices for a ticket are stable around $10 or $11 everywhere you go.
As for the commercials, I hate watching so many of them too. Lots of theatres have slideshows filled with advertisements that play non-intrusively before the movie, and I don;t mind these since you can choose to tune them out if you want, and there are usually games and trivia scattered between the ads (though some chains now have audio to go with their slides, and this sucks big time).
There should be nothing but trailers before the feature presentation. But since some places like putting literally 10 to 15 minutes of COMMERCIALS, not even including trailers, you have to exercise the only power bestowed upon you as consumers, and either complain by writing a letter or simply shop around and see if there's a chain that doesn't put as many ads on. Where I live, there are three movie theatre companies. Two of them are big on the 5 or 6 commercials in front of the movie, but their ticket prices are about $1 less. The other chain puts maybe 2 ads before each movie, but have a slightly more expensive ticket price. All you have to do is figure out whether you'd rather spend more money or watch more ads.