If it's too formal that's their problem.

Also, I would never give one of my 10+ phone numbers to someone who I wouldn't give an e-mail address to, except maybe my one junk/spam number.

It's awesome, because you can send larger amounts of data, works across countries and across SIM cards, can also be read on laptops and tablets if you don't have a phone with you, etc.

I once had to give a restaurant a bad review for requiring a phone number in their in-person, dine-in order workflow. I just told them that I don't ask for their wait staff's phone numbers and require it to be a customer. They shouldn't require mine, either. I have cash and credit cards and having money in hand should be enough to be a customer. Period.

I was able to use fake phone numbers for vaccine appointments and most other things.