I don't know if you're just genuinely stupid or just playing the role here. Either way, there's no such thing as an EU passport and not all countries which are members of the organisation known as the EU get 30 day visa exempt entries to Thailand.
them questioning or denying entry to probably 0.001% of daily visitors isn't going to cripple the industry.
For what it's worth I entered Thailand about 14 times last year, maximum stay of 3 weeks but usually just there for long weekends.
Previously lived and worked there, legally and not on visa exemptions or tourist visas, for 3 years. Never been questioned once, including my most recent entry 10 days ago.