I literally hate when services and apps force me to use SMS-based authentication.

When I travel I need to use a different SIM to access reasonably priced internet. Because I don't have a double-SIM phone, that means my other SIM is not active at the moment.

Really dangerous trend is when this SMS confirmation is requested when I don't expect it. Once I was in the Philippines and AirBnb wanted me to verify my authentication attempt. It can be not only frustrating, but dangerous - I have accommodation scheduled and without the access to my home number I could be easily left on the streets in a foreign country.

And my last complaint -> SMS can arrive pretty late when you are in a foreign country. Sometimes too late that the authentication window is closed.