The total sartorial ignorance of most people under 50 is awe inspiring. How can so many people live so many combined years with no knowledge of proper dress?
Speaking as one of those who is under 50 and trying to learn "proper dress", I can tell you it's because society doesn't care about what's "proper" any more. You older fellows apparently were taught somewhere, or picked up the rules of etiquette along the way. But for us younger folks, we were raised in a time where etiquette was (apparently) not important. It's not like they teach this stuff in school. And it seems that your generation failed somehow to pass along your knowledge to mine. Nowadays people expect the rental/hire companies to know the rules for formality (it's their business, after all!), so if these companies are responsible for bad information, shame on them. For normal people who do not attend enough formal functions to have been exposed to proper etiquette, why would you have expected them to know all the rules?

Many of us are trying to learn from you older and wiser gentlemen, and we appreciate your help on these issues. But I can't help feeling a little defensive when being labeled as "too ignorant to know better", even if it's an accurate statement. You may not have intended it to be demeaning, but surely you can understand how your statements could be taken as such, especially from the folks who are genuinely asking for help.