If they avoid calling it a proximity bonus and call it an on-call bonus, legal may have some footing to pass on to HR. Though this is only an issue for existing operations.

If its an 8 hour workday, being able to make hypothetical emergency briefings at the office within 2 hours with no/short notice may be worth a 25% salary hike.

Its the new remote first companies that will exclusively hire for skill and balance the equation once the next wave gains more traction.