Cartels are formed to fend off competition. That's why they engage in anticompetitive practices. Cartels engage in price fixing because they are no longer competing against members of the cartel and therefor use their position to exploit buyers. Banks have nothing to do with that particular behavior. The state is an extension of the market, and through regulatory capture, enacts laws and regulations that enable the cartels and monopolies to function while preventing significant competition or innovation. This is a fact that you can't seem to understand, but you should learn about before continuing to talk about markets because you seem very ignorant on the subject.
The trading you describe is barter, not a sophisticated monetary market of the kind generally discussed. I agree that barter is better, but it is impractical on a global scale.
No. Cartels are formed by 2 reasons:
1) Illegal collaboration (if their industry is illegal, they need organization to survive otherwise they end up in jail: drug cartels, maffia, etc.)
2) Uneven competitiveness resulting instant monopolies or oligopolies
Now nr 1) is obvious, no need to explain that.
However nr. 2) is your usual cartels (oil,bank,pharmaceuticals,contrsuction,etc.)
Why did nr.2 came into existence. It was because a handful of people got rich too quick and too early, and they were able to bribe politicians to enact laws in favor of them. These industries are not today born, the banking system exists since the 1700, sure they had time to bribe everryone.
And back then it was even easier, because there was only 1 king that needed to be bribed, so the nr 1) monopoly has always existed.
If we would start again humanity, with no kingdoms, but with current technology, I would guarantee you that no cartels would exist, since there would be nobody with sufficient power to be bribed, since everyone would start off small and be competitive from the start.
It's only when you have a 300 year old cartel that got the early power from the kings, you cannot bring in the free market here as argument, the nr.1 monopoly there was the kingdom itself.
------------------------------
I wasnt talking about barter there, because you put take 1 intermediary, between the 2 items, that will be the currency, and have the same system, but much more liquid.
It can be done in global scale, as you can see how, however a non-inflationary currency , like bitcoin would be more efficient.