The free passes are to entice people to buy more. Whales are gonna be whales and hardcore F2P are gonna be hardcore F2P but that's not who Niantic caters towards, they go for that "middle class" of players. People who may ignore a bad/non-shiny legendary but would raid it with a free pass and heck, if there's a 2fer or 3fer they can do with that same raid group they might plunk down a few bucks to do the other raids, that's who Niantic has to entice to pay for passes. If nothing else those free passes ensure regular activity amongst players which can then lead to purchases just by nature of people opening up the game more often. If we weren't remote raiding in 2020 Niantic would have suffered enormous losses on the year. A lot of countries are just barely getting back into the swing of things as is so they're not going to be thinking about IRL raids regardless so PoGo might go days or weeks or more without being opened but if they can get people to open the app more often with the enticement of a free raid then all the better and it's costing Niantic almost nothing to do this stuff anyway.