Are forever stamps really that hard to comprehend for most people?

I think half my route today was still using 41cent stamps, if they weren't using 39 and 37's....lol

The other half of the route was affixing TWO forever stamps on every letter, or putting pennies on top of their forever stamped envelopes.

I'm wondering if the message just isnt' getting across :/

Something else that I've always been bothered by: Why is it when new stamps come out, half of them will actually SAY 41cent and half of them will just have the art, with no postage displayed? How on EARTH are customers supposed to know how much they are worth? We only know because we see them a thousand times a day. Customers are using really old stamps, but there is no postage displayed on it, so how can I say, hey you need 5 more cents on this without making either of us sound stupid? It's a big waste of our time to have to tell people this anyway, they just need to print the price on ALL STAMPS darn it!