When using OSM Scout Server, its either natural for your country/language (should be parsed by libpostal) or from street number to milky way. See Parsers in https://rinigus.github.io/osmscout-server/en/

The online services, I assume, have their own preference.

I will get one day to work on geocoder of OSM Scout Server and will then look into improving the situation. That's the largest weakness, I think, in OSM Scout Server currently.

Edit: corrected the order, sorry for mixing up.