I used to work in optics and in order for plastic/acrylic/resin to be made U.V resistant it has to be left in U.V solution which is contained in pots at quite high temperatures, close to boiling.
So I imagine that the bags aren't as it would more than likely melt, be damaged from the heat.
Yep they are just standard plastic bags. You only get the full UV protection with the archival cases although they reckon that the standard AFA cases do give a degree of UV protection.