I’m afraid the world is not black and white but full of shades of grey. If you don’t want to grind gems, then grind plants, sell them, and buy gems. I think the footfall is root of all evil. Because footfall is free coin, and you think that you should get tons of it, hell… you even want to steal half of footfall from every player, and redistribute it like communist did want to. If there was no footfall, but you had to trade resource you gather for resources other players have it would be way more fair. The shops are orthogonal to grind.
Again, you misunderstand what freedom is. It’s not having everything for free (creative mode in many games), it’s being able to achieve anything you want, given you put enough effort. There is no bounds to where or what to build, or where to go (of course bear CoC in mind and other players plot too).
Again, your misconception is that you are entitled to any money beside those that you get from doing feats, tasks. You get footfall if you are able attract people to visit your plots. But it’s your, and only your duty to make those plots attractive. Easiest way? Make an attractive portal hubs. Or build roads near portal hub in strategic places.
Also freedom means, you don’t have to spend a single coin (beside those on warping) to craft, or gather anything in game. Everything, really everything you can get, if you put at least some effort into it.
600 buy means 60 lost to taxes. 850 sell = 85 lost to taxes. 850 - 85 - 60 = 705, so his margin is about 15%. I wouldn’t call it unfair.
Still vote with your wallet, don’t like the prices? Find better ones, or sell your gems by yourself, and put out request basket if you want them cheap. That’s also one of the aspect of the FREEDOM you talk so much. He has a freedom to put any price he wants, you have a freedom to buy or not to buy.