Today I watched this video of a couple sharing their experiences avoiding Biometric scans in South America, which are common place there as well. They talk about their experiences such as having to wait an extra hour in Peru while they figured it out. They were able to opt out of everything in South America, but these countries don't have formal laws for biometric entry/exit - I don't think the same strategy would work in the EU, but I hope to be proven wrong.

https://youtu.be/YnAh1CvTQcE