I'd like to say that there's no way I would do that for a kid in Compulsory levels, but each case is different and if I had had a super talented, very young gymmie with incredible potential I'm not sure what the answer would be. For a "regular" gymnast like my own (10yo L5, no elite potential) the answer would absolutely be no, I would not drive 3hrs/day for gym.
Our gym is about 15min from home, other DDs dance studio is another 15min away (and 30min from home). I drive back and forth between those every evening of the week plus Saturdays. I work at gym so I don't go home in between, I just go back and forth between gym and dance depending on who has what schedule and when I work.
We do have families who drive 1hr each way, 5days/wk. that's dedication. To be fair, I will say that those kids do have loads of potential and I might be tempted if I was in their shoes. They do have a closer gym but it's not good at all. Our gym has much better training and coaches, and one of the girls in particular wins pretty much everything, every time she competes.
I do also agree with whoever said that it may be just as, if not even more, important during the lower levels to get good training, BUT I think I would have to really be very realistic about my kids actual potential before making that decision. At this age/level, so many of them end up quitting and it's only a select few who will actually stick with it long enough to make those early years training truly worth it, KWIM? It would be nice to have a crystal ball and be able to say "little Suzie, who shows great potential now at 7, is actually going to quit and do dance team instead at age 10" or "Betsy, who is a tenacious but struggling L8 at age 13 could have really had a chance at this if she had only had better training at age 7..." There's just no way of knowing how it will play out.
I always think get the best training you can, it's never wasted (in both dance and gymnastics) BUT it has to be within reason and only you can decide what's reasonable for your family. For me, it would be unreasonable to drive 3hrs/day for L4 training.