When I looked at living in London I did not expect a Single family home, or even a terraced house. My expectation was a apartment, or even a room. And I was willing to pay a lot for that room. Because it was ‘London’.
But London isn’t the entirety of the UK. People in smaller cities might very well expect to live in a house by age 30 or so.
Same as New York. Many people live in apartments here, but people in Water Gap, PA are more likely to own a house.