I don't think it's fair to call richer services lockin. GAE has lockin, in my opinion, because basic services use GAE-specific APIs and common needs (like scheduled jobs) are accomplished in uncommon ways.

If you're using auto-scaling or beanstalk or whatever, that's an example of AWS offering something where there isn't a norm, isn't a "normal way" to do it, and if you need that thing, your other alternative is to build it yourself - which is still an option should you decide to move away from AWS.

Lockin is avoidable switching cost which benefit the party imposing the switching cost. Are there examples of AWS doing that?