I don't really understand where this belief arises from. Most homes in the US are built on undeveloped land. It's not typical to tear down an existing house to build a new one.
To the extent that it happens, it's generally because an area is essentially undergoing redevelopment. i.e. a rural area is being consumed by an urban city. In cases like that, the purpose is to increase density. It's pretty rare to tear down a single family home just to construct an equivalent but newer one on the property.
To the extent that teardowns are more common in the US than the UK, I imagine it's driven mostly by the ability to massively upgrade in the process. If you live in a 150-year-old stone house in the UK that's been updated over the years so that it's got modern electrical and plumbing and already maxes out your square footage (meterage?), what would you gain by tearing down except a lot more debt and some better insulation? With that said, I think this math generally doesn't work out for Americans, either, who generally trade up homes rather than rebuild.
https://www.google.com/amp/s/amp.theguardian.com/cities/2017...
There is also a mentality of homes being forever. My house was built originally in 1870 and that's not particularly old. In the US old homes (except perhaps in a few stylish old areas) are something which need torn down and rebuilt.