Swiss 3a retirement accounts - catch 22

I noticed that some Swiss banks will only provide retirement savings accounts to people who also have private accounts at the same bank, and private accounts seem to cost money.

Basically you have to pay for a private account in order to get a "free" retirement account. What is the deal?

Banks are free to create their own policies regarding who is eligible for certain types of accounts (such as 3a accounts).

Certain banks only provide 3a accounts to customers who have private accounts with them. Other banks only provide 3a accounts to people who reside in certain regions.

When limitations apply, these are clearly indicated in the moneyland.ch pillar 3a retirement savings account comparison.