We have a similar push for RTO here in Germany as well where the usual U.S. centric reasons don't apply (tax break law has not changed; we're still semi-ZIRP at 2%, no H1B visas, outsourcing is not a major trend either as many companies want German speaking employees).

I think the reason is simple: Lock-in for employees. Moving for your employer demonstrates dependence and highlights your inferior bargaining position. If you have to move again to switch jobs it will be quite painful so you'll likely accept a lower salary instead.