Sure, but if you don't have "a couple of hundred dollars", you don't. It's a bit like saying "Why are people poor? Just put $1 million into a savings account, then you'll get enough to survive each month". Great for the ones who can, irrelevant for the ones who can't.
Don't forget you have to buy books, etc., and they cost "a couple of hundred dollars" too.
When I was an undergraduate I was definitely on a knife's edge, but I also often had cash in the bank because I got a big cash infusion annually. I just had to live off a very strict budget at that time to make sure the money would last.
I wouldn't have wanted to rely on this service when I was a student, especially at that cost, but in a pinch I could see situations where it would make sense.
It would have been nice if I did though.
People going to university like to talk about how poor they are, but they're obviously not "can't manage a couple hundred bucks for college" poor. I've known a lot of constantly-bordering-on-homeless people, and they're usually lucky to even manage community college. UW is $13k a year just for tuition.
If you can't get into a required course, it can delay your graduation a full year. That costs way more than a couple hundred dollars.
I ended up needing to stay an extra semester for a single course my final semester, because I planned poorly and discovered too late that I couldn't get it in my would-have-been-penultimate semester.