Why is a business allowed to refuse a customer?

Because also freedom of contract is a right. Except for discrimination on the basis of protected categories, a person or entity is entitled to discretion on whether or with whom to do business and enter contracts.

The last sentence in your post reflects a misconception of "completely different set of values and laws" between the USA and members of the EU. A comparison of the Wikipedia link you posted and, for instance, 42 U.S.C. § 2000e-2 reflects an overlap of protected categories in the laws of the Netherlands and of the US, such as religion, sex, race, or national origin/nationality.

One would need persuasive evidence to support a finding of unlawful discrimination in the two examples you have experienced.

Assuming the bank responded to your GDPR inquiry truthfully, the bank's refusal to open an account might have stemmed from profiling or decision-making that (1) does not precisely require specific data about you, and/or (2) uses information the bank does not need to log for purposes of compliance with the GDPR. Note that the GDPR does not outlaw algorithmic decision-making.

Since legislation in the EU (as in the US) portrays an approach of market economy, both bank and landlord are entitled to made decisions on the basis of their inner policies for risk management. The policies might be unclear to you, but that does not necessarily mean they contravene principles of equal opportunity.

Why is a business allowed to refuse a customer?

Because also freedom of contract is a right. Except for discrimination on the basis of protected categories, a person or entity is entitled to discretion on whether or with whom to do business and enter contracts.

The last sentence in your post reflects a misconception of "completely different set of values and laws" between the USA and members of the EU. Clearly there are many differences, but a comparison of the Wikipedia link you posted and, for instance, 42 U.S.C. § 2000e-2 reflects an overlap of protected categories in the laws of the Netherlands and of the US, such as religion, sex, race, or national origin/nationality.

One would need persuasive evidence to support a finding of unlawful discrimination in the two examples you have experienced.

Assuming the bank responded to your GDPR inquiry truthfully, the bank's refusal to open an account might have stemmed from profiling or decision-making that (1) does not precisely require specific data about you, and/or (2) uses information the bank does not need to log for purposes of compliance with the GDPR. Note that the GDPR does not outlaw algorithmic decision-making.

Since legislation in the EU (as in the US) portrays an approach of market economy, both bank and landlord are entitled to made decisions on the basis of their inner policies for risk management. The policies might be unclear to you, but that does not necessarily mean they contravene principles of equal opportunity.