In the modern era in developed countries squatting is now largely just trespassing, which is illegal, but there have been periods where that wasn't the case.

Most notably, following the two World Wars you had a large number of young men (primarily) that died overseas with corresponding effects like their family might move as a result and so on. So you had a large number of vacant properties with no clear idea if the owner was still alive or not. So squatting became a way of "solving" that problem. A squatter could get the rights to a place if they occupied it for some long period of time (typically over 10 years) if no one showed up earlier to claim ownership.

In the computerized records era, and with no mass casualties from war in developed countries, this is now relegated to an historical anachronism.

> that usually requires either consent and active participation of previous user at the same address or proving that you have legal right to use the property.

That's the key. Where I live, it only takes online applications to sign up with power companies and telcos, if infrastructure is already in place (cables laid, power meters installed, etc) and it's not associated with any active contract. After sign-up, services are remotely turned on and kept on as long as bills are being paid.

It's not up to service providers to police property rights. They own or have rights to infrastructure leading up to the final junction box and what happens downstream is not their business.

In the countries I've lived in (IT, GB), utilities are not routinely shut off when somebody leaves the premises, nor does the utility company know (or care about) who is or is not the rightful owner of a given property. As the last occupier, you just tell the company you're leaving on day X and that's it. Squatters come in and just keep using pipes, or even take out new contracts in their names.