Yes, It is cultural. And I think It is more than what you described, Although I may be over generalising it a bit.

If you look at the US, all of the large tech companies, or in fact any big companies, not just tech all have the same mentality. Rule the world. Whether that is Finance, Energy, Food, Tech. The home market US was merely a testing ground, they always had an eye on the world. They are greedy, pushy, willing to go the extra miles to close the deal. The sales forces between US, UK and Continental Europe are very different. Where in UK and EU there are more towards making both party happy. US tends to be ruthless.

US tech communities and companies also has a rather strange workaholic culture. Where employees are expected to put in the extra hours. But of course the pay in US is also a lot better. It also gives the idea that if you wanted money, go to US, or even working in a US company in the UK, or remote. Most UK / EU tech companies are not salary competitive.

Management Style is also different. Which also mean the working environment in tech also flavours US companies. Some of what is common in US is against the norm in UK. This matter in Tech because the space is moving way too fast. Innovation Efficiency is the key. Before you could gasp the basic of one thing you already have to learn another. Compared to other industry you mentioned which tend to have a slower pace, even in finance. what you learned dont change that often. Only the Data changed.

Not to mention the Brits culturally aren't very good at marketing. Something the US is exceptionally good at.