>Why do profit margins matter at all here? It's only a signal that there is a problem if margins are very high because there is no guarantee that an entrenched monopolistic company will be efficient or make a strong profit.

If they were really wasting ~20% of their revenue someone would buy them or do a hostile takeover.

Unless they are spending most of that "wasted' money on capturing markets and paying legal firms to stomp out any potential competition. Or the constant advertising campaigns for services that me and many others have never had access to. I see comcast commercials every day, ive never lived in an area with comcast available. Just because they aren't making huge profits doesn't means they are spending that money on providing services.

Why risk innovation when stomping out competition is much more straight forward and predictable?

Do you have any numbers showing that any of these companies spend somewhere in the neighborhood of 20% of their revenues on capturing markets and legal firms?

If they are in a low competition (natural monopoly) market, maybe open books on where the money is going should be a regulatory requirement.

the wireline operators are mature companies, amazon is investing heavily in growth. this is an obvious distinction. courts and regulators constantly apply this sort of informed judgment and nuance to their analyses because it's required for their jobs.

I agree there are big differences between these ISPs and Amazon. I was just making the point that Amazon's lack of a profit wouldn't exempt it from these regulations either. Profit is as much a bookkeeping/tax/business policy as it is an actual market signal.

You can only fake it to a certain extent since you report cash flow. Even for cash flow from operating activities Google (35%), Apple (30%), and Facebook (52%!) outshone Comcast (25%).