TCG mid is a serious problem. Vendors rely on uninformed buyers who look at TCG with their quick phone apps and see a giant number that legitimizes a price. They know the cash value is lower, but when some kid shows up to the trade tables with a binder full of highly liquid standard and modern staples wanting to pick up his first power, or some old Legends card, that arbitrary price means he gets taken to the cleaners. Vendors look at $1500 Tabernacles as an opportunity to take in $2000 in buylist which they can flip for cash faster than the one kid looking to build Lands. It's not malicious; they're just being good stewards of their own inventory and looking to turn a profit. Business is business.
In many ways, we were better off in the days of Scrye. Internet sales were supposed to pinpoint the true value of cards, but in reality it has just become an unregulated market for speculation. The tools we have available are too easily manipulated. I wish a popular site like TCG would start calculating mid prices as an average over time, rather than a snapshot of a single moment. If it took 30 days to drag the needle up on old cards, it would be a lot harder for people to spike a card and cause a panic.