Honestly, I'm surprised to see Seznam on HN. I grew up on Czech internet in 90s and Seznam.cz (or "Directory" in English) has been huge for long time until Google has eventually beaten them. The vibe I get here from comments is like as if Seznam.cz is some new hot company while it is really a dying dinosaur like Yahoo.
Maps are not core competency of this company. They are early Internet pioneers maintaining huge portfolio of various services for almost two decades. Maps is just another service they are working on to keep users from leaving them for Google/Youtube, Facebook etc.
Btw, I spoke to Seznam.cz founder briefly once at some business event in Slovakia back in 2000 when I was 17
edit: their maps are created by Melown.com, see example https://www.melown.com/maps/