Airlines are worried about surviving. They have your cash. It may not be legal to keep it when flights are cancelled, but most customers will take what they are offered (future travel credit) and very few will complain to authorities.
Qatar Airways though has a better approach. They, too, want your cash. They want your future travel purchases when travel is again in the cards. They are honoring refunds but if you’ll take a credit instead they’ll give you a 10% bonus for taking a voucher. That’s creative and honors the customer.