(Partially answering your "why", not commenting on whether the original statement is true.)
"the average health insurance cost for employers was $16,253 annually"
https://www.peoplekeep.com/blog/cost-of-employer-sponsored-h...
Now some employers in the UK add private health care as a benefit of course.
https://job-prices.co.uk/private-health-insurance-cost/
Average is £74 a month, or $1200 a year.
(Partially answering your "why", not commenting on whether the original statement is true.)