The ID and address proof are (for my country which is part of EU) required when getting close to certain treshold in yearly recieved amount. This happened to me quite some time ago and it did not result in change of my account type. It is still personal.

I had a personal account for one of me and a business account for another of me. Same as eBay, you can have multiple accounts with the right CC and bank accounts. But that's a side topic.

When they stopped having free transactions for sales it became a moot point. Some people I know tried to send small sales through "gift" transactions and got caught. This is PayPals way to increase income and charge for everything. Might as well change account types and play by the rules. Transfers and gifts are still free.

https://www.paypal.com/cgi-bin/webscr?cmd=xpt/Marketing/general/PayPalAccountTypes-outside

Personal accounts are also subject to volume limits of $500 per month. If you receive more than that, you will need to upgrade to a Premier or Business account (or deny the transfer that would have put you over the limit).

Personal accounts can't accept credit cards.

If it is, open another account !  you can have more than one !! 
.

We would be charged a fee if the agencies wouldn't pay it for us.

I think it's called "Masspay". The agencies any possible fees for us - at least the bigger ones do so.

I think the last one of the "bigger" agencies that used to charge was Canstock but that was many years ago (back in the day with BW television lol).

I can only speak for myself having a Premier account.