Within the EU, it would likely be considered an invasion of worker privacy (indiscriminate screening of where employees are logging in from). Even if it weren'

Within the EU, it would likely be considered an invasion of worker privacy (indiscriminate screening of where employees are logging in from). Even if it weren't an invasion of privacy, as you say, companies want to be able to point and say 'look, we have a policy, you aren't allowed!' and blame workers for breaking the rules rather than trying to solve the (admittedly complex) tax regulations about working outside the country you are normally employed in. But it's also convenient not to know.