Not so, I'm afraid. The Federal Republic has operated a continuous improvement programme for many decades. Not many stretches of the autobahn system are still as they were built in the 1930s - most have been improved, widened and have had hard shoulders added (there are a few original stretches without shoulders, but even they are due for upgrading). And of course, the 1930s system, whilst putting even 21st century Britain's system to shame, was only the start of it - their mileage has been quintupled (or better) since 1950. Just look at a German road map, compare it with a British one - and try to stifle the urge to laugh.
I wonder where you get that idea from, because it really isn't true - at least, not for important parts of Germany that were democratic. Yes, as an example, the old Flensburg bypbutt autobahn (on the Danish border) is as it was in 1939 (resurfaced, though!), but it has also been bypbutted - totally - further west by a new Hamburg - Denmark motorway that crosses the Kiel Canal on a spectacular, toll-free, high-level bridge.
good shotThere are plenty of viable alternatives that could be developed, but whilst certain companies make huge profits from IC powered cards it won't happen...
It *is* true that the German "Democratic" Republic almost completely failed to maintain the autobahns in "their" bit of Germany, but even so, those autobahns have been very substantially upgraded since reunification - especially the A2 (Hanover - Berlin) and the stretches of the Berlin - Munich and the Berlin - Hamburg autobahns which were within their control. You may not know that the socialists' incompetence in those matters was legendary - an oft-repeated "East German" joke (ostensibly criticising the Nazis) was that they should be forced to come back to Germany and fix the motorways they had built.
The socialist government seemed to think they would last indefinitely with no maintenance. At least, that is the only explanation for it. They seemed to think the same of buildings, including the workers' homes.
Do we have an East Germany (an entire region devastated by socialism) to rebuild?
Perhaps we do...