They are from Prague (Czech Republic). While not SV, I can assure you they could easily find VCs there (or abroad, maybe in Russia?) if they wanted to.
Not everyone's goal is to build with investors' money. Sometimes it is easier to succeed without it.
" I can assure you they could easily find VCs there "
It's not a question of 'easy or hard' it's a question of 'easier or harder'.
Being in Czech definitely makes it harder, hands down. Thankfully, they are in the EU, but it's still a completely different land that many VC's might not be remotely willing to touch. Consider that very few can even read the laws.
Czech startups would be limiting themselves to German and possibly Russian money in general, and it'd be harder to raise in the US.
JB is a great company that might be able to 'easily' raise money, but even then there could be 'red lines' for many firms that just make investing there impossible. For example, a firm may require they re-incorporate in London or Luxembourg or something, where there are far better established commercial laws.
I know many European startups raising money from American VCs.
Open Delaware C-corp and hire European programmers remotely. Either via consulting agreements or wholly-owned European subsidiary. Our company (tensorflight.com) did that.
After fundraising with both European and American VCs, indeed the VC market in the USA is much better.
Not everyone's goal is to build with investors' money. Sometimes it is easier to succeed without it.