EU trade

Advertisement near our boat harbour:

Lively Dutch
ANGLING WORMS again to delight us
50 gr pot 5,90
(name and address and mobile phone number)
ALSO ON SUNDAYS !

5 meters from the advertisement you can dig living Finnish worms.
How do you know, if they are really Dutch? Do they speak Dutch, or/and do they have stamp: Made in Holland.

In harbour were these Estonian father and boy (?) angling. I didn´t ask, if their worms were Dutch or Finnish. Maybe Estonian.