Counterpoint: if you think you need to pay for my attention, that's a negative signal for what you're asking me. If I'm giving 10 vendors a shot at my business, I'm not going to pay money for the right to give you that opportunity?
On the other side, the only person paying $5 to ask me something is probably someone getting a lot of no's elsewhere. That, or what I offer is so valuable that people are willing to pay for it. But that's not most people.
Of the 20% of mail that is useful to me, it's still pretty much all just from corporations who have decided to send me a physical letter even though they have my e-mail - e.g. the water company sends me some brochure to somehow justify how much money they're charging by breaking down what they spend all their money on etc...
I get almost zero "real" mail from actual people nowadays. Now it costs £1.80 to post something first class and 91p second class, real mail is basically limited to birthday and Christmas cards. I myself send so few letters, than I still have a couple of stamps in my wallet that I technically bought 6 years ago when they cost 35% the current price (although they were replaced with barcode versions by sending them in to Royal Mail).