Is anyone 100% conforming? Is your point the "slippery slope"?
Perfection is the goal. Some in these sects feel they are already there and demand conformity, even though its unrealistic. Slippery slope is the definition of why a "geder" would exist. So some of these prohibitions are gedarim, gates, to prevent from entry onto the slippery slope.
Driving is one I have never understood though.
When my older son started high school, at orientation, they warned us of modes of transportation available to the boys. Every successively more sophisticated mode of transportation allows for a bigger radius for the kids to run away to. So they implored us not to get the kids drivers ed to keep them closer to home.