In the UK it's very common, albeit not for 30 years - more often 2, 5, or 10. See e.g. https://www.bankofengland.co.uk/bank-overground/2020/why-are-more-borrow

In the UK it's very common, albeit not for 30 years - more often 2, 5, or 10. See e.g. https://www.bankofengland.co.uk/bank-overground/2020/why-are-more-borrowers-choosing-long-term-fixed-rate-mortgage-products https://www.bankofengland.co.uk/bank-overground/2020/why-are... (In 2020, more than half of new mortgages were fixed for 5 years or more.)