I also believe that to be the case. Unfortunately I do not have access to zero commission brokers. It would have been quite easy to test.
Tastyworks seems like crap to me. Never looked if they even have an API, I doubt it's anything close to what IB has. I'm still surprised there are so few players in this segments when it comes to automated traders. IB earns a buttload from API traders and there's almost no competition. Everyone tries to lure the average Joe with their "pretty" platform, for which API traders don't care about.
I love the freedom that comes with being a trader. But I have grown extremely dependent on IB and I don’t like being dependent. What the few alternatives for EU residents have a in common is low equity and no real advantages. Except for Schwab if you live in Germany, UK, Switzerland or Spain.
Why would they restrict your trading to only 10% when they're being paid for selling your order flow? Wasn't that the reason why they moved to the free-commission model?