I don't check before I drive and don't ever have any problems. If I feel low, i'll check but even if I get home and check and it's high I know I've never had a problem with driving while high.. I don't think it's really something to worry about, but if it's what your mom wants I'd respect her wishes.
same here i never test before i drive unless i feel low or i had to treat a low less than 20mins before. the only time i'll stop and test is if i'm on a long drive(i.e. the almost 5hour drive from home to tofino) and i don't feel "right" or we're just stopped for a leg break..but for those kinda trips, i usually have just eaten so i've tested before we head off. i don't usually keep food in my car either, but for longer trips i always have a few cans of coke and snacks in the cooler that no one is allowed to touch, so if i do have to pull over, i've got food.
i've only had to pull over once for a low..and that was about two years ago now. highway driving while going low is really dangerous and not fun..
for the first while, it might be a good idea to test before you get into the car for sure just because it's all new, and always test if you aren't SURE how you feel...but i don't think i even did that when i was learning to drive..my mom usually asks me before i go out what my last test was anyways, but she's never asked me to stop and test before getting into the car.(i think she's forgetful like that lol)