The smaller roads and tracks you can see there are all missing even in the latest OSM maps for garmin that I found. I tried both the MapSource installers and the ready-to-use gmapsupp.img, as well those of Computerteddy (eu.tgz and typ_eu_gmapsupp.img) as those of Lambertus (http://garmin.na1400.info/routable.php).
I am sure they were visible in those garmin maps a few monts ago! Does anybody know the reason for that? Is it a problem of the rendering sofware?
It seems the default Mkgmap style includes aeroway=runway, but not aeroway=taxiway. So anything tagged as a taxiway won’t show on the Garmin map (if using the default Mkgmap style).
I think the Lambertus maps are using the default style.