Yeah of course, there are many things that are widely believed but are false. But we were told this in a 30 minutes course a doctor was giving, in a campaign the schools were doing to educate us about the danger of the sun. A few other things were told, like that there is no total protection sun cream or that even cream that are marked as water resistant do not resist water. That's when we learned that 1mm of "modern glass" would cut nearly all uv light, while it requires nearly 50 meters of water to block it.

Of course not all that might be true, but as far as I know, it is pretty accurate.