Yes of course if you buy a whole bunch of stadium food it is expensive, but one of the entire gimmicks of the baseball stadium is that they make most of the money on beer and food. The thing is, food is optional! This is a form of progressive pricing that allows the team to charge people who are price insensitive more while still being affordable.
Most baseball stadiums also have constant or frequent promotions for seating in the outfield berm, or standing room only, or last-minute walk ups, etc, which are very cheap. I recall walking up to the Astros stadium and getting $8 tickets just as the game was starting. So if you really want to go to a game but you don’t have very much money, there are usually ways that you can get in for very cheap.
Parking is weird to include because it varies a LOT depending on the setting. Much like the airport, there are usually unofficial parking options just a bit further from the stadium that are much cheaper than the official parking - though this is less true for the suburban stadiums.
One last thing is to note that the experience at the stadium has changed enormously. Stadiums in the 60s were basically a bigger version of high school bleachers. Now they’re luxury palaces.
What has really happened is the stadium experience used to be much more equal, and now it reflects and capitalizes on increased economic inequality - offering wealthy fans a super-premium experience for a ridiculous price.
I think that’s the actual problem. What used to be an extremely “democratic” past time is now an extremely unequal experience. And while I don’t think that is baseball’s fault, I think it’s a negative reflection of the broader economic changes since the 1950s.