You're contradicting yourself. You can't have "regulatory capture" and "deregulation" at the same time.
As a matter of actual fact, we do have lots of regulatory capture, which has resulted in huge swaths of regulation that favors large corporations who can afford lobbyists, and disfavors smaller business that actually are the most productive part of our economy. With what results, we see.
> They are effectively not enforced
Antitrust law enforcement has indeed been irregular since they were passed--but what enforcement has been done has done more harm than good. The classic cases of antitrust enforcement, such as Standard Oil or Alcoa Aluminum, resulted in higher prices and scarcer products for consumers--i.e., a negative impact, not a positive impact.
However, antitrust laws are a very small part of the total body of regulations that affect businesses. It's just that most of those regulations are written by executive branch bureaucrats instead of Congress. The Federal Register is much larger than the United States Code, and includes much more detailed micromanagement of all kinds of business activities. Which, again, favors the large corporations that bought those regulations in order to hamstring their competitors, smaller businesses who are more productive but less able to absorb the costs of compliance with that huge mass of regulations.
The only regulatory capture in play against antitrust is bribery of the judicial system officials, which we now know is rampant, and employing executive and congressional pressure on the DoJ, which obviously exists.
This is probably the best example of government lack of regulation, considering that their ample laws against monopoly's, cartels and duopolies from the days of Teddy Roosevelt's administration
They are effectively not enforced, or if enforcement is attempted corporate legal departments now have an effective means of defeating them since the Microsoft trial