@Mateusz ***
Most of us figured they would bring this with the new ETA system. It seems they have shelved ETA, and it might not ever happen. I think it will happen eventually as it's the only realistic way for them to start collecting the tourist tax they've been talking about for YEARS.
The system we think will eventually arrive will that you submit the ETA if you are arriving without a visa, and then you'll know long before you travel to Thailand whether you'll be granted entry or not. Submit ETA, pay the tourist tax, and then get approval or denial. If you get approved, you go straight to the auto gate when you arrive since they've already recorded all of your information and your approval for entry. It's what makes the most sense. Rarely does that aspect matter for Thai policy though.