Because the culture of US medical training was initiated by a coke addict, and it's extremely conservative and slow-moving.
https://en.wikipedia.org/wiki/William_Stewart_Halsted
https://en.wikipedia.org/wiki/Medical_resident_work_hours#EU...
https://www.theguardian.com/society/2009/nov/05/nhs-confiden...
In the UK they always worked long shifts because it’s safer. They’re trying to stop them, and it’s less safe.
Why do you think the reason the UK has always worked long hours is due to a drug addiction in the US rather than experience in safety?
It looks like they are not hiring enough senior staff, not handover problems.