I've heard a few people say this now about the Manchester ones. I don't think a bus across the M62 is everyone's cup of tea when trains are quicker and a lot .ore regular. In regard to the York ones I can only say what I see. A few times I've seen 0-3 on, more times when there's been less than 9/10 on and a few times when they look relatively busy (15+)
We'll, yes, the train is faster, but the same could be said of pretty much every bus route (with broadly parallel rail service) - the train competes on speed and the bus competes on price.
This is a railway service where people on this Forum bemoan the lack of flexible fares under £20.
The bus doesn't have to be "everyone's cup of tea", it just has to find a niche in the market - and the market is potentially big enough for there to be scope for a fast train (TPE), a slow train (cheaper fares on Northern via Hebden Bridge)
and a bus/coach service, as well as thousands of motorists.
Just look at Edinburgh - Glasgow - two cities of broadly similar size to Leeds/ Manchester that are roughly the same distance apart, where there's always been a regular coach service (Citylink, Megabus, M8Motorvator, Stagecoach and various others over the years) as well as a fairly frequent train service (that is much faster than the coaches).
I've not been on a CityZap, I don't claim to have any knowledge of their operation/ targets/ profitability - I just think that you're going out of your way to find things to complain about (e.g. reporting every broken down vehicle on the service).