https://www.cnbc.com/2019/04/24/tuition-at-public-universiti...
It is therefore not a question of affordability but a question of priority for most families. If they cannot set aside that much money it is, bluntly, because they chose to spend their money differently.
Edit: Apparently the average price paid for a new car in the US is $37k [2]... So basically the same as the average price of a 4 year degree in-state. People make their choice.
[1] https://www.thebalance.com/what-is-average-income-in-usa-fam...
[2] https://www.boston.com/cars/car-news/2019/06/09/average-new-...
The $76k figure is median across all US households, I’d be more interested in the median amongst those aged 25-45, which is basically the ages you’d be saving for university (and even then you have to take into account that your income at the start of that range is not going to be what it is at the end).
It's not unreasonable to charge tuition fees that are significant enough to make sure student will choose seriously and study diligently. I say that because it is certainly not always the case in countries where university is free...
It also makes sense to provide scholarship for deserving student who could not otherwise afford it.