InPost is essentially useless in the UK, mind... there's essentially no retailers that support it, you can't have arbitrary packages from retailers posted to one, and I've literally never seen someone using my local InPost box to send packages. I'm assuming they're burning through investment money badly. To show how little people care about it: it doesn't even have an English-language wikipedia page.

If they could somehow have the postal service and couriers able to post things to InPost boxes, it'd be far more useful - but I suspect there's some really complicated contractual stuff that prevents that.