It also doesn't make much sense from a productivity standpoint. Whenever I did on-call, it would obviously disrupt my sleep schedule and my work performance the next day would be... suboptimal. Follow the sun makes much more sense.
BTW, follow the sun is getting more complicated. Lots of large contracts in the US (and almost anything adjacent to the gov’t or their contractors) require US-only data storage and access now. I’ve worked with enterprise customers who were adamant that none of their data can leave the US under any circumstances, including having a subcontractor in London provide support.