a) Don't have to pay to fly candidates out, pay for their hotel, etc.
b) Don't have to pay relocation
c) Get access to a larger pool of candidates, so can price the wages lower than local wages would require
My last company there was a top down directive that in-person interviews were straight up not allowed, everything had to be over Zoom. Even for local candidates, for a job that was supposed to be in-person! Completely crazy IMO.