Why does GM charge more for an Escalade than for an LTZ tahoe with all the same options and ride quality?
Because they can...
Better you're WAY overgeneralizing. You cannot get all the same options on an LTZ tahoe than you can on an escalade. I worked for GM for 14 years. The first 13 with Chevy and the last year with Cadillac.
You cannot get surround vision on a tahoe, you cannot get massage seats on a tahoe, the escalade has a bigger engine, nicer and more expensive headlamps and tail lamps. The entire interior is better on an escalade. Better leather, better carpet, better door panels, better dash. Full digital instrument cluster.
You can talk about "ride quality" but they don't use the same part number shocks. The list goes on and on, but I've driven both and if you can afford it the escalades are worth the extra $$$. If you can't afford the premium, then a tahoe is a worthy substitute.