Startups and economic development
That's not a bad fit for relations between startups and GDP. The number of startups in the dataset seems to be a good indicator of entrepreneurial activity in general.
Here's an illustration for Dan Senor and Saul Singer's thesis about Startup Nation:
Israel has relatively more startups than the US. Tel Aviv and Silicon Valley drive the numbers for their countries, so it's not exactly a nation-wide phenomenon. You call the book Startup City, though the result is no less impressive.
Web data and language barriersLike other sources based on voluntary reporting, CruchBase may have data biased on one or another way. For example, it may underrepresent countries, in which English is not a major language. And we expect a bias in favor of bigger firms. And here's the case:
The surprising break after the 90th percentile separate countries into two groups. What are the groups? Look here:
Group 1 are countries with < 0.02 startups per 1,000 inhabitants and Group 2 are the rest. And in result Group 2 contains countries with an explicitly high role of English language. So, the break indeed looks like a language thing.
Nevertheless, language per se is not a big factor in development, so it doesn't bias the data on GDP in a systematic way. (You can also control the very first plot for the percentage of English-speaking population.)