That's sometimes true but often not. Utah might need buses to go up the canyons, but might have passed some requirement at some point that said that all the buses need to be able to do this because someone got burnt once by not having enough of those buses. Or some well-meaning (or vote seeking?) city councillor might have put through a bill to put USB-A chargers in all the seats, which will stick around far longer than those coming as standard making them an expensive custom option.
What you end up with is requirements that make the buses custom purchases, which massively inflates their costs, when any reasonable person would say that such custom attributes aren't (always) needed. By having a strong opinion about something, the city will pay far more than if they bought an off-the-shelf solution.
Much of "the west" is particularly affected by this sort of attitude. Everywhere and everyone is convinced that they are special in some way and need something specific, but end up paying for it. This is part of why India can send a probe to Mars for $72m, or why Singapore can buy busses at $300k instead of $1m. And to be clear, I say this having grown up in the UK and moved to Australia, both places with a certain amount of this attitude.