You shouldn’t give out your real email address. I instead use randomly generated email addresses that forwards emails to my real one. I can easily deactivate any forwarding email address and therefore stop any unwanted emails.

It works really well and also has other benefits like for example knowing who sold your information if you start receiving spam.

You also gain a bit of privacy and security from being a tiny bit harder to track and your credentials being less valuable in the case that the company you gave the random address to has a data breach.

This video explains the concept very well.

I worked in one of the biggest telecom companies in Europe. This is most likely an order made through customer service. The telecom companies have known about this problem for a long time. They are trying balance security and ease of use for the customer.

If company A implements noticeably stricter requirements for identification to order stuff, the average customer gets annoyed and switches to company B.

Therefore the companies watch each other closely and implement stricter requirements slowly at about the same rate as their competitors.

Protip: You can contact customer service of most telecom companies and ask them to write down a password that you need to tell them before you can order a SIM or other stuff.