The biggest motor racing changes in that period were probably not at F1 or "stock car" racing venues, but at Le Mans (due in part to the horrific crash there in '55). Ever see that video on YouTube? Chilling.
What is remarkable about the Le Mans accident a that the race continued to completion after more than 80 spectators were killed.
Yes, many times. F1 had some bad ones in the early years also. And a few in the latter when they used pressurized fuel rigs.
The NASCAR Boyz in the early years would just light up a smoke in the fire on Pit Road stand back and let it burn out on its own;)