Actually, the networks literally built the infrastructure to transmit from the White House. They’re the ones with the resources to do it daily. That includes a considerable amount for staff, equipment, & travel costs. We then pool footage to other outlets. It is a public service.
The “primary White House TV pool” is a completely made-up thing dressed up to look official. It is basically a group of self-important, so-called media organizations that, over time, appointed themselves “primary” and now expect everyone else to accept that they are entitled to some permanent special status above everyone else.
The whole thing is a racket made to look like an official institution. Why does anyone still buy into this crap?
Anyone with a camera can provide this footage. The White House itself could provide it. Any other organization could provide it. There is nothing inherently special about this self-appointed group, except that they have spent years telling everyone there is.