Eu citizen being asked birth certificate for AMKA

So I came in Greece to work in hospitality in an island. The restaurant initially, for the contract, asked me passport and name of father and mother. After 1 week they came to me and told me that I need to give also a birth certificate: first for the tax number, then after I discovered it was not true, it came out that it is from AMKA.

Now, getting a birth certificate abroad is something challenging that I already started to do but...

Is this normal?

I worked in other EU countries and never had such requests.

Thanks all in advance