TCR cars aren't that expensive or difficult to run, which is why there are nearly 800 of the things racing in all sorts of events globally.
However, running a car in TCR UK seems to be expensive. You can't charge BTCC money for something that isn't (or claims not to be) the equivilent of the BTCC in the very same pond
Perhaps the whole thing would make greater financial sense if it were on the BGT program, where teams could amortise costs and pool resources? A team with a GT3 car in it's stable, wouldn't be over-reaching to run a much less-involved TCR car at the same meeting. Teams that run in GT Open and ADAC GT Masters have been doing it for a few years now. Aren't there teams that run BTCC and BGT programs in parallel? Easy to see why some haven't considered doing TCR, as that'd be another 8 weekends of the year they'd have to contend with.
I love the concept of TCR, but as for it existing in the UK, they need to make some radical changes. Tacking it onto a club racing calender as per last season, did nothing for it. There's almost zero incentive for anyone to get involved in it. A young bloke wouldn't even do it to get his name out there. What else is there, to aspire to in the career ladder?