The 'monopolies and cartels' scheme is fear based in nature. The point is to tell people that those around them, with whom they are in voluntary relation ships, are conspiring against them in back room, secret cartels, price fixing or dumping schemes. This might seem more likely to the tax subject if he himself is part of a price fixing scheme like a trade union with legal protection. Voluntary cartels and monopolies suffer from competitors who undercut each other's prices secretly to gain market share. Legally protected price fixing schemes can hold out longer as is proven by the government itself along with many industries with legal protection against competition. Anyone trying to undercut the prices of the legal monopolists, will be thrown in jail by you. 

The problem with posing as a fighter of monopolists and cartels, is of course that government itself is a monopoly. A further problem is that the monopolies you claim to fight (voluntary price fixing) never existed in history for a decent amount of time. Some violent person is required to stop competition from moving in when profit margins are above average. Even with the force of government, it is as hard to stop people from moving into profitable markets, as it is to stop bees from moving to flowers filled with honey. The solution to this, is to make some monopolies with force and create more monopolies while fighting non existent monopolies. Of course only your supporters get awarded monopolies (unions, patent protection, tariffs, environmental dictates) and only your opponents get accused of running monopolies.

By this time you might wonder how you can arbitrarily accuse your enemies of running a monopoly while giving your friends one and running one yourself. This can be done because markets can be defined narrow or wide arbitrarily as you wish (fully backed up by academics on your payroll). If a cola producer A is not handing you enough taxes, you can say it has a too big market share in the market for colas. Once you squeezed more money out of A, you can redefine the market as 'sodas' and conclude A no longer has a monopoly. You can go further with 'beverages', etc. etc. The theoretical groundwork for this has been done by defining 'perfect competition' in such a way that no market is perfectly competitive and your forceful intervention is required every where to make it so. Since this definition is full of contradictions, you have lots of leeway in interpreting it any way if favors you. Funding academics pays itself back generously. Compare for example what is said about the 'Robber Barons' by academia inspired writings and what actually happened.

In the past (during the great depression), governments forced companies openly to become member of a monopoly (to raise prices, which supposedly would create jobs), but this has since went out of fashion, probably since support of monopolies in broad daylight is hard to enforce as it advertises to investors and businessmen where to go for high profits.

Questions to avoid

-Are you against monopolies on principle?

A tricky one for obvious reasons. Start injecting a lot of fear to shut down the part of their brain that came up if a question on principles.

-My marriage is an exclusive relation ship, in which my partner and I limit supply of our love to the market and have a written agreement to always exclusively deal with each other. Is this against government regulations?

A person asking such a question is obviously trying to trick you.

-I am part of a union which restricts supply of labor to raises prices, while I remain legally protected from being fired by my employer. Am I violating anti cartel legislation?

This question will not be asked if the tax subject is sufficiently scared of losing his job. Fear of job loss can be arranged by making alternative jobs illegal with e.g. minimum wage legislation or by price fixing the wage at an artificially high level. Since this will raise product prices, import should be prevented by tariffs, otherwise the company goes bust. 

Remember to keep good control of your own monopolies