FYI, you can definitely rent a car younger than 25, you just have to pay more
On Enterprise's website booking, they have three age options...
25 & older
21 - 24
18 - 20
For 21-24, they add a Young Renter fee of $20 per day (which is about 50% of the rental price). Except they won't rent this age a 12 to 15 passenger van.
For 18 -20, they say they won't rent you anything (at least at Wichita locations).
Seems like they are still discriminating.