In Germany the neighborhood network nebenan.de does try to expand in a similar way. They use a special service by the German Postal Service Deutsche Post, which allows you to have non-personalized leaflets dropped into letter bins within a designated area. While this is less personal than a letter with a name on it, it is also much cheaper.
They are now present in about 1,000 neighborhoods which have between 30 and 600 members according to press. I am not aware whether or not the other two companies trying to build a market-share with a neighbourhood network service here in Germany (nachbarschaft.net and WirNachbarn) do the same thing or use a similar postal service offering to address people locally.
However nebenan.de started a year later than WirNachbarn yet seems to have reached an equal number of people by now. Scaling such service here in Germany though is much harder in my opinion. Neighbourhood watch groups are basically unknown over here and organising one therefore is no trigger to join such a service like it is in the US.