Don't some of them do detective work from height , looking at garden house buildings etc. looking for people who live in these, out buildings[ thermal , heat sources ] - who should NOT live there , especially on cold clear frosty nights ..
Don't forget those ' warm ' cannabis factories also ...
As the technologies get better ..
Yes TFC, they're based at the home address, well 2 out of 3 were! There were trails when you zoomed in to the max, but just a few metres here and there caused by what I can't guess. Definitely suburban and not spacious properties either.
As to the planes using thermal scanners, they should try in the London borough of Hounslow, they might find thousands of 'garages' in people's gardens producing a lot of human thermal heat.