EU GDP is about 2/3 US GDP. That’s a very significant difference. Per capita income is probably less important than average and median disposable income, which is much higher in the US and has an obvious impact on B2C companies.

FB was incubated in a single unified market before it really spread to the EU. It’s harder for companies to take off and reach tech giant reach with the much smaller individual markets in the EU.

It’s much harder to build a product that appeals to everyone from the Irish to the Bulgarians, and to advertise to them than it is to do the same for everyone in the US. And it’s not just the tech companies, the individual content creators on the platform have the same comparative problems.