Sorry Pete,
In general and in principle I agree with you, too many bureaucrats is not enough as far as they're concerned. But when it comes to high-speed hijinks, there are just too many variables to account for. Skill levels, car condition, road condition, weather, wildlife, etc. etc.
As to the Autobahns:
"Millions" is I think, an overstatement.
Having commuted between Waldorf and Frankfurt three times a week for 23 months I can attest that of the many
thousands who drive the Autobahn(s), every day maybe 1% drive in the 'no limit' lane and most of them at no more than about 140-160kph.
If they don't scare themselves ****less, they run out of petrol long before any serious mischief occurs

( A GT2, Enzo, Murciellago or Veyron at flat-chat will be skosh juice in about 4-7 minutes).
Also, the Autobahns are
always being repaired and covered in 50kph zones, so the average speed is closer to 70kph than 100+
Mercedes make big, beefy, buggeringly-fast cars to appeal to those who like same, and God love 'em for it!. But the 'Green' lobby (hiss! boo!) in Germany is ALWAYS after them (and BMW and Opel and, and, and,....), so I would take their "Studies" with a massive grain of salt! As I would Porsche's or Ferraris or 'Ghini's
Skill level, car design,(brakes?), climate and geography all mitigate against high-speed roads here. While the Monash and that horrible stretch of road north of Sydney, might be perfectly respectable commuter highways they are in no way equipped to handle speeds in excess of 120kph. Not with the traffic they carry.
Doubtless there are hundreds of roads in Australia where you could, safely exceed 250kph (my driveway is one

), even if you had only yourself to kill, but why risk it?
Anyway, driving 'quick' is a lot more fun than driving fast, IMHO of course!
ATB
Peter