Why isn't the US the "land of the free" also in VoIP?

I don’t understand the US American market of VoIP devices. The PhoneBoy tells terrible things in the VoIP Weblog:

It seems that the VoIP providers are just as bad--or worse--than the mobile phone carriers in the United States, which generally don't let you take your phone to a competing provider. Unlike with US mobile phones, where there are two standards, pretty much all customer premises VoIP hardware speaks SIP, the lingua franca of VoIP. Just recently, I threw a Vonage-locked Linksys ATA/Router combo that Vonage refused to unlock for me. What a waste!

And Garrett Smith explains "How to Unlock SunRocket Gizmo For Use With InPhonex".

"Poor Americans", must I say. Why do they accept ATAs that are locked to just one provider? Because they don't know it better from their mobile telephony? Why do Vonage or Sunrocket users have to throw away their hardware and cannot simply use it with another company? Why doesn’t PhoneGnome admit that “Free calls between PhoneGnome members” is a normal feature that is available with every other VoIP provider. It’s called "on net calls" and nothing special.

In Germany we use open devices, such as Fritz!Box, where you can install up to 10 VoIP providers of your choice. One of them can be PhoneGnome, because it also supports the open SIP standard, but it doesn't have to be the only one.

With intelligent ATA dial plans you can assure to make only free on net calls and to always use the cheapest provider for your other calls. People use to play around with the cheapest routes of the various Betamax brands, depending on where they are calling to, and they like to install several of them at the same time.

In the USA, in contrast, VoIP devices are commonly locked to just one provider. Like cell phones that you have to throw away when you change the provider.

Is this really the "land of the free"?