In this modern age we expect and want everything right now. Not after your suntan has faded, slightly gnarled through the postbox, from a trip that you took over two months ago. The rising cost of stamps, too slow snail mail and instant digital information are all affecting these little cards lives.
I've heard horror stories of hotels who are blackmailed by guests into getting a discount or otherwise they will receive a bad review, and those who get bad reviews find that it does impact their business. No great shakes if you're the Hilton maybe, but for a small business owner it can be devastating.
Fake online reviews are not particularly hard to spot. When they're glowing, full of marketing speak, and from a new commenter, this should raise a flag for website owners and users. On the other hand, some hotels and restaurants have complained about malicious and unfounded reviews, some of which come from rival companies.