It's that pesky car culture that is getting in the way of humanity again. Part time riders, full time drivers…
Now clearly, trail centres need to be in areas with good riding ie. the middle of nowhere. But I would have thought that some provision for alternative transport at some point in the planning process of choosing areas to develop should have been discussed. Bus links, areas with good potential near towns, that sort of thing. As it is, you mostly need to drive. Ironic…
I don't know if you've heard of http://www.bikebus.net and I realise they are not close to you, but maybe there is a similar thing nearby?