I'm not a car guy but I most certainly a bicycle lover, so I will jump on you and say you often need more than one type of bicycle. Joan commutes to work? she wants a city ebike. Dan rides at the bike park? He wants a DH bike. Randy ride centuries on the weekend on his TDF road bike and Sally rides with her kids on a mountain bike.
So yeah, we can pick one bike type and force everyone to ride it, and the results will suck & everyone hate it. Your job can be to continually force everyone to follow this policy or you can stop and we'll get a lot of variation. THis is how it happens.