> What's more, several cell phone operators' plans include unlimited WhatsApp, but only a few GB of other data... meaning when your data limits are reached you can still use WhatsApp for the rest of the month, but not i.e. Signal or Telegram. That makes is rather hard to convince people to switch.
not fair. it's not a normal service. it's a transportation service. If I can't travel on date X, traveling on date Y may be useless.
One could argue it would be useful for another trip to a different location. Sure. But because airflights prices are so shady (prices changing every day, prices that are different if you have a VPN connected, etc etc), the voucher could make you choose for the worst price.