I now have 200+ accounts in my Password manager. Sure, I know I'm part of the 0.01%. But I can't imagine that there's anyone who does own a smartphone but still has less than 10 online accounts somewhere :) You just need them for too many basic necessities of life these days.
It shouldn't be so much of a barrier, and if it is, they probably need help even with setting up Signal or Whatsapp too. After all that requires a google play or apple account to install from the store too.
Have the employer or pension provider deduct any applicable taxes, and the rest gets paid to the payee. If they do not live in a country where that happens automatically, they could still hire a local accountant.
> Sign up for electricity
Can be done by phone. But if they already have electricity in their home, then even that is not necessary.
> or a mobile phone?
This can still be done in store. In some countries, in-store is still the only way.
An online account may make some of these basic necessities cheaper and more convenient to access, but it is not the only option.