This is actually one of the correct ways to deal with lead paint, assuming the "paint" is actually a proper encapsulant. See for example https://www.health.ny.gov/environmental/lead/renovation_repa...
The EPA, for one.
https://www.epa.gov/asbestos/protect-your-family-exposures-a...
The problem is inhalation of fibers, so if the fibers are not in the air and inhalable, they pose no risk.
Don't ever trust anything a real estate agent tells you, especially if that agent stands to gain financially from your actions; they are the "used car salesmen" for houses. They lie.
>only one case did another ever admit to knowing of a problem where signing off on the proper lead paint/radon/asbestos warnings.
A problem? Like the existence of them? You should test for radon before buying a house, so you'll know. I have friends who turned down a house with high levels of radon because the seller wasn't willing to negotiate for radon remediation. Lead paint isn't a concern as long as it is undisturbed, however, you need to treat every house built before 1980 as having lead paint. Asbestos? I have asbestos in my house, which was disclosed to me, but it was professionally wrapped, so safe as long as it remains so. Pretty much every house that's as old as mine contains asbestos, at least in my neighborhood. So it doesn't effect the value of it at all, as long as it's wrapped.
Same goes for old ceiling panels, often loaded with friable asbestos. An act as simple as drilling a hole, or installing new can lights can load up the room with airborne fibers if done carelessly.
Government buildings are always suspect, as they often are exempt from many building codes, including fire codes.
I also remember the barracks I lived in had old asbestos floor tiles and the walls were covered in lead paint. They eventually renovated the barracks, and instead of getting rid of the lead paint, they just painted over it. The asbestos tiles weren't dealt with, and all they said was "just don't use a floor buffer and you'll be fine". There was also a cleaning station where we'd clean our rifles, no safety warnings or instructions were given, and we thought it was just a cleaning solution. Later we saw a warning sticker on it that said to use full eyes, face, and hand protection because the cleaning solution could cause neurological damage. Just waiting for health probelms to crop up once I'm older :/