I mean that’s just how acceleration works. Speed is distance over time, acceleration is change in speed over time, hence distance over time (speed) over time
That’s not the problem. Coming from metric, I expected m s-2 for acceleration. The imperial units for distances are weird enough in their own right – but using two different units of time for the two time derivatives is truly unholy.
See I glossed over that because that’s an entirely nonsensical issue. Do you measure the speed of your vehicle based off how much distance you cover per second or per hour? And then there’s the fact that it’s a math problem, written at roughly a middle school level - half the problem is figuring out how long it takes them to get up to the desired speed and if they did that in a person hour scale it would leave almost no math for the student to do
Especially in a middle school math/physics setting, I would expect reasonable units. Otherwise, how would kids understand the relationship between force and acceleration? Do you use mile / hour / min for the acceleration due to gravity as well? Do you have a funky replacement for Newton too?