Because these loans will be (mostly) paid back. And both the Treasury and the Fed are lending a lot of money to people, through mortgages, at extremely low rates.
Yeah, but in that form, to which portions of the population are the fed and treasury indirectly lending via mortgages? Are the people in a position to benefit from that lending the most important people to assist? Is their spending going to optimize some multiplier that gets the fed the most impact for each dollar lent? Or could they have a larger effect with an intervention that injects money to some other group?