I live in Berlin in an area that has many parking cars. I rarely hear an alarm go off. Maybe 2-3 times a year, if at all. I also only know this from anglo-saxony media.
Car alarms seem very rare in some countries. On VWs used car portal in Austria out of 670
VW Passat only 22 have a car alarm. I never had a car with an alarm and never saw a reason to get one.