Undergraduates with family income below $200k will be tuition-free at MIT

This is a great step in the right direction. I can't speak directly for MIT, but there are issues with how these programs don't apply to parents with small family businesses. My parents had a small business, with my father taking home a salary of $XX,XXX. Duke University used the business assets to determine the EFC (expected family contribution) of literally 90% of the salary. Essentially saying to sell off the family business for the college fund, which was a non-starter.

Small businesses are allegedly the backbone of America, and I feel these tuition support programs overlook this segment of the middle-class.

Why are such things in the US so complicated? Where I live, studying is much much cheaper for most professions,for everyone!

That's the only fair way. Also, a set of well educated people pays itself back later in the form of mostly income and added value taxes, which provides money to keep studying for cheap for the next generation.

the ideal is that college should be very expensive for rich people and cheap, free, or at least more affordable, for less wealthy people.

american universities get closer to this ideal than you might expect. the days of outrageous student debt are thankfully fading away, at least for undergraduate degrees.

it would make more sense to do this redistribution through taxes if possible, but many US institutions are private so that doesn’t really work. so the colleges basically have their own privately-run means testing programs, and like all such programs there are flaws and loopholes.

Why should college be very expensive for rich people?

Because they can afford it. It's a redistribution tactic. You can also phrase it like this: college should be free for all to attend. Then, as long as you have a progressive tax scheme, the outcome is the same. Cheap for the poor, expensive for the rich.

Then are you suggesting buying anything should work like this?

Are you suggesting education is like potatoes?

I would say it is more a service, like a massage or a week in a resort hotel.