Only employers who have very low skilled workers do so, for two reasons, one is that skilled workers have more power to negotiate better deals, the other reason

Only employers who have very low skilled workers do so, for two reasons, one is that skilled workers have more power to negotiate better deals, the other reason is that these gig companies operate on thin margins, in fact most of them operate on loss so every dime that can be saved is worth it. They only survive because they are subsidized by billionaires investors. Eventually most of them will either go bankrupt or find a way out of their loss at which point they will be able to increase their workers salaries (as it is a good thing for productivity and attract more talents). There's a lot of animosity against "evil employers" or "lazy workers" but it usually is a bit more complex than these simple dichotomies.