The only problem is that they OWN most of the cables and most other providers need to rent at least the "last mile" or maybe even other parts of their infrastructure (i.e. 1&1 uses Telekom DNS services) so there is a big chance, that others will follow :/
But they only rent the last mile from the Telekom. Starting at the DSLAM they usually bring their own infrastructure. (Except reseller contracts).
In the last years there also have been many small, local ISPs popping up, often partly owned by the city (Stadtwerke). Some start rolling FTTH connections and finally bring germany to the internet-first-world.
Cable providers, at least Kabel Deutschland (which is the only option here where I live), are sadly no alternative, while they offer high bandwidths without volume based throttling, the traffic shaping they do at peak times and for torrent traffic is ridiculous and makes their service almost unusable.
I am lucky enough to live in Cologne we have fibre in almost every household (NetCologne) so I don't really worry .. But still most people have to rely on Telekom offerings cause there are no other options.
In Berlin the situation is quite bad. There are these moronic DSL providers, which deliver the connection when they feel like it. It's quite expensive, slow and there are interruptions quite often.
The alternative is Kabel Deutchland. Their connection quality is pretty ok, but the throttling every evening when I get home from work is annoying as hell.
What I really miss from Helsinki is that when you order e.g. a cable connection, they'll deliver it the same day when you made the contract. It's fast and reliable. No throttling, no limits.
Although I understand why the situation is what it is. And still I'm not complaining, this connection is good enough for the most of the time.
Well, we're not so lucky in Backnang. It's the year 2013 and still, my connection keeps randomly dropping as if it's making a tribute to the dial-up days (tried many adsl providers; no luck. I haven't tried Kabel BW though.) I guess the situation is similar in many other small German cities?
To be picky ... Most other providers aren't resellers of Telekom plans. They own their own infrastructure and only have to rent the cables going from the distribution box to the customer's house. And this line is not charged by the traffic or bandwith. And Telekom can not change the way how they charge this line. There are federal regulations for that.
And to be specific, as customer of 1&1 I seem to be having a VDSL connection (50M) like any other T-Online customer. My host is some *.t-ipconnect.de and Youtube is as throttled as it is for a direct contract. If they now add bandwidth caps on top of that, they can go screw themselves.
So that's why YouTube is still so flaky even on my 50Mbit connection. That's ridiculous. With a 200GB data cap, what's the point in paying for that? I use 500GB/month without even trying.
I think O2 is also just a simple reseller of Telekom's VDSL. So apparently we have a competitive market for standard DSL up to 16Mbit (if you're very lucky, but often well under 10Mbit in practice), but not for the current generation of highspeed internet.