Why can't we contact yahoo directly?

Because Yahoo has no phone number support at present. Those 800 numbers have no connection with Yahoo.
Those 800 numbers charge you and cannot do anything to help you but take your money.

Yahoo has no direct customer support, email, or phone numbers you can call. This is the only support Yahoo has: https://help.yahoo.com/kb/helpcentral

or you can try the new Yahoo Help forum: https://forums.yahoo.net/

Because they don't employ any staff to answer the phones.

How much do you pay Yahoo for their services?

you "can". there's just no phone number to call. https://help.yahoo.com/kb/account start with that page. go to the contact us link to chat with someone.