I can’t put a SIM in my ereader or Switch or iPad.

Convenient to connect all devices to one WiFi. E.g. baby camera is on same WiFi as laptop etc.

Changing countries a lot reduces this option a bit.

I’m sure I could find a good all Europe card, but I need my number for work calls.

In Europe you have free roaming so it (almost?) never makes sense to get a new sim per country.

You have roaming but sometimes it’s less data than at home. And you can’t use it for months on end. I have multiple sims from various EU countries. When I visit I top up.

To be clear. Within the EU. Not Europe.

EEA, not EU. I had to check as I thought UK was also included. Seems like they left?

UK is not included, but most UK mobile networks have chosen to pretend the UK hasn't to their customers, and offer similar amounts of voice and data in the EEA, so it still mostly works "one way".

I think it's the other way around? Most UK networks seem to charge charge now (the big ones anyway, EE, Vodafone etc.).

At least in Germany, none of our networks do.

I'm with O2 and most certainly does not get charged extra when travelling within the EEA.

They're the last large one that does not charge.