Lobbying involves quid-pro-quo: You pass the bill we wrote for ourselves and we give you a cushy consulting job when you leave Congress.

As Matt Levine points out, the revolving door often works in more interesting ways.

If you are a bureaucrat, the way to maximise your next paycheck is often to be especially tough on companies (and on the margin push for more complicated rules that you can be an expert in). Simplified, the logic is "See how tough I am, you better give me a good paycheck to make sure I'm playing on your team."

The beauty is: the bureaucrats at the regulator don't even need to consciously think this way. They can be tough out of the ideological and conscientious conviction at the bottom of their heart, and the mechanism that gives them comparatively higher pay afterwards still works. Being tough also raises your profile, when you are but a junior or middling drone.

The logic you are describing might work, but only for the most senior appointees who already have a high profile.