while riding a bike to, say, a school would be practical, sometimes you can't ride bikes everywhere. some people weigh too much and run out of energy, bikes break more easily, can be stolen, and in most cases, are too slow, and some routes take hours on end and are too slow. not to mention the long rides that take 10 days of cycling. overall bikes should be used more though.
:/ the point is to not waste energy. making it faster would ruin the point of inventing it. also, 68 mph is 109 kilometers per hour! that's not a low limit. especially because this is in France, where speed limits are about 60 kph. idk about American limits but I think they are higher.