come on, the simple fact that there is a Facebook group for people who are confused about the visa rules proves that the websites are not that clear. I live in Thailand already for some years. But when i try to understand the rules by reading Thai government websites I only get confused.
European law is for Europe. Not for European citizens in Thailand. Thai companies targeting citizens in Europe should also follow the European laws. Same as US companies targeting citizens in Europe also have to follow the European laws.
That is why I told you. In the 5+ years that I am flying back and forth 3 4 5 times a year the airline OR did not ask OR telling then that I would get an extension was ALWAYS enough.
I had flights many times (all my flights) with a return ticket for a later date. Just telling them that you will get a visa extension in Thailand always solved the problem. You are making him worry too much.
I never tried cards from Thai banks in the 7-11, only foreign debit cards. But my Krungsri Visa card and Bangkok bank Mastercard (debit) work fine in gasstations...