There are many limits to technology when it comes to hunting in Colorado. Some of them have already been cited: drones,optics on muzzle loaders,optics and any electronic on bows, electronic calls, scouting by plane within a 24 hour window of hunting, etc... in case you can’t tell, social expectations and legislation combined with fish and wildlife department recommendations regulate this. So if you are surprised or upset by this, move on to the next state.
IME overseas, thermals are devastatingly effective in open terrain. The same terrain that optics are effective in during day light with a diligent and trained eye. In timber the target is not identifiable until the trees become thin enough for the bits and pieces of thermal signature to coalesce into an identifiable form.
Personally, which doesn’t matter to you, I have other priorities for spending my limited expendable income. Elk are out there and easy to find during the off season. Harder at times to find during hunting season and that’s the nature of hunting.