I feel like the global market is flawed in concept. If people are contributing goods to the shop, they will usually choose whoever is on the top of the list first or whoever has the most of the good they are looking for. It makes sense that people can supply to meet demand, but having the vendor's name on the list causes a level of bias. An example would be if Charles was selling 10 burritos, while XX_vccoolgammarSCP360_XX is also selling 10 burritos. Almost everyone is going to buy from charles, considering the fact that he's well known, he's an admin & he's also got a better name.
Potential solutions: anonymous vendors. Vendors would be completely anonymous, removing the bias of names or personal relationship. The items in global market would just show up as items, and you can select what you want.
pooled inventory. if 10 different people sell a bunch of burritos, possibly the entire inventory of burritos should pool into one giant mass of goods. It'll show up as "83 burritos available" instead of "vendor 1 is selling 10 burrits, vendor 2 is selling 5 burritos." this will eliminate people buying vendor 1's burrits over vendor 2 since they have more of that burrito. The problem with this is that individual vendors may not make any money, and the 'highest bidder' per se will sell the most.
Maybe with a pooled inventory, you would buy a burrito and it would come from a random vendor, they will earn profit. Or maybe, when you buy a burrito, each vendor earns the percentage of the burrito market that they are currently sharing, which means that if 10 vendors put up a total of 1000 burritos, each vendor will earn like 1% of the sale, while if 2 vendors are selling 4 burritos, each vendor will earn 50% of the sale.
Another example: Phanto is selling 10 burritos, charles is selling 1. When a burrito is purchased, Phanto will earn 90% of the profit, while charles will earn 10% of the profit. Phanto will stay in the market because it's good, but Charles might see that he's turning too little of a profit, will recall his burritos and instead move over to the salad market, where he will dominate and earn most of the sales.