You can't compare the firms you are describing to legit prop firms. I can tell that you are not familiar with these firms by your arrogance and ignorance. To your "impossible" statement that a prop firm can give better commissions than a broker... We are talking about 3-6MS DMA paying fractions of a penny per share vs "free" stock trades which aren't DMA with low latency executions... come on. Any pro trader would rather pay than get free internalized trades that don't execute at a reasonable time. "Just use your own money" is pretty distasteful, as if everyone has a modest 5 figures to leverage into small 6 to just make a living. There are a ton of math major grads who have student debt who apply at prop firms as a job, no deposits or education. Yeah, just your own money you dumb poor kid, how stupid are you? lol.
The futures prop firms have a completely different business model than the equity prop firms. A futures prop firm registered with the CME is required to only risk the firm's capital, not the trader's capital. They will also have to pay you on a W-2 as an employee. Examples are DRW, TransMarket, Wolverine, Jump, Prime, Geneva, Belvidere.
Any place that is too good to be true will have more chances of being a scam. Be aware of such scams.