in 1967-68 when I was a young police officer, I can remember the many complaints I responded to about the kids sniffing that stuff and getting high, and there was really nothing we could do about it because it was not illegal at the time.
Laws against sniffing "glue" I don't think any would have an issue with. Gas belongs in an engine not up someones nose. Paint belongs on items{car, house, tractor} but not up someones nose. I don't get ID'ed when buying gasoline which from what I have seen is a much more abused substance then liquid nails. Maybe those sniffing glue etc.... are just helping to weed out idiots in society? There are laws against abusing materials but why should the innocent be harassed when they are using the product for it's intended use?