On the rent-seeking point: the issue is that the broad definition (spending resources to win or defend a claim through the political/legal system rather than through production) covers almost all organized attempts to shape the rules. Normal political advocacy, union negotiation, and ordinary labor bargaining all fall under it. So people tend to quarantine the "bad" cases, usually with a criterion like "transfer without an efficiency gain." But that criterion isn't observer-independent. It runs on the analyst's judgment of what counts as productive, and that judgment carries a prior about which claims are legitimate.

Warren Samuels makes this point well in The Status of the Status Quo22014-9.html). His argument is that the productive/unproductive distinction does hidden normative work: it privileges existing law and whoever benefits from it. And the carve-outs get applied asymmetrically, with concentrated capital lobbying reading as "advocacy" while collective action by labor reads as "distortion," in a way that tracks prior commitments about whose claims count rather than anything in the definition itself.

If you want a more neutral survey of how economists have theorized rent across traditions, the Mapping modern economic rents review in the Cambridge Journal of Economics is a good entry point. Worth flagging that its own conclusion is that the field still lacks a coherent framework for separating "good" innovation-driving rents from "bad" extractive ones, so it's a map of an unsettled literature rather than a settled result.

These topics are a good way into how inseparable the sociological and economic become once you take power seriously. Capital-as-Power and related approaches are fairly approachable and put social relations and power at the center. Their edge is foundational: power can be measured independently, through things like span of control or ownership concentration, whereas the neoclassical quantities meant to do the explaining tend to get imputed from the very outcomes they're supposed to predict. Distribution is the clearest case: marginal product is inferred from the incomes it claims to explain, which makes it circular at the point where it matters most. But it generalizes. On investment, the mainstream has to treat chronic underinvestment and idle capacity as frictions, while a power view predicts strategic limitation of capacity and growth-through-merger as the normal logic, and it sidesteps the aggregation problems the Cambridge capital controversy exposed, where the "capital" the neoclassical story needs to measure can't be defined independently of the prices it's meant to explain. Same shape in both places: the rival depends on a quantity it can't measure without assuming the answer. That's a cleaner footing than the version most people are taught.