>I have no doubt someone could break into my house and install hidden cameras without leaving a trace
Yes, but it feels like it would be hard to do that without the risk of witnesses. Sure, you could probably muddy the waters by claiming to be official or something, but it only takes one person to actually check your credentials or call the cops or even just tell the person "Hey this person went into your house, did you hire them?" to blow up your spot.
Pretty much all of your examples require some level of home surveillance, either neighbors or a good camera system. If you don't have nosey neighbors and don't have alerting cameras, it would be almost trivial to pick a standard lock and place a few small mics or pinhole cameras while the house is empty during work/school hours.
The real deterent here is that nobody cares enough about some random normal person to do this. It's much easier to send email spam to trick a tiny percentage of gullible people into believing it and paying up.
Yes, but it feels like it would be hard to do that without the risk of witnesses. Sure, you could probably muddy the waters by claiming to be official or something, but it only takes one person to actually check your credentials or call the cops or even just tell the person "Hey this person went into your house, did you hire them?" to blow up your spot.