German drivers are objectively WORSE than MOST American drivers, speaking from experience driving thousands of km/mi in both. German drivers completely unnecessarily accelerate very strongly, take corners quickly, and slam on the brakes when stopping much more so than in the USA. The main difference I can attribute fewer deaths to by observation and critical thinking, is that Europeans have to be far more vigilant of random stuff appearing on the side, since many streets can have cars randomly coming from the right side because of what qualifies as a secondary road, and in some cases, you must yield to them, so the paranoia is much higher in towns. Of course, there are way more stops and crosswalks, cyclists, and pedestrians in most European towns, also elevating ones alertness. Finally, speed limits in European towns are much lower than anything in equivalent US towns because everything is more compact. Also of note is truck speed limits in Europe are generally 80 KILOMETERS/H whereas American truckers frequently drive north of 80 MILES/H. Cattle haulers are known for going 90-100 MILES/H on I-10.
That would train higher reflexes in the drivers.
I drove in Rome, Italy, for 8 years and another 7 years in Canada.
While Rome is far more dangerous because of the stuff that happens on the road, the drivers are way more ready to avoid incidents.
I have no idea if this is better or worse,just giving my perspective.
I find driving in Canada very relaxing,but it often puts all my senses to sleep,which is scary.
Also nobody shoulder check left when turning left in Canada (Vancouver). That's a 100% kill of a scooter in Rome,because the swirvle between the cars.
Not driving like a grandma is not a big security issue if drivers are accordingly trained and expect it. Not looking for other participants, especially pedestrians, is one.
Considering driving and road rules is entirely learned behavior that requires tens / a hundred hours of training before they let you do it unattended, it seems pretty reasonable that the environment you learned in plays a pretty big impact on how you drive.