It's been said before, but communism looks good on paper yet doesn't work in application. Then again, capitalism doesn't work very well either, considering the huge imbalance between rich and poor which exists in basically every society. In short, communism is too balanced (in its purest form) and capitalism isn't balanced enough.
This gets a little nit-picky. True capitalism doesn't exist - nor does true communism.
For two interesting reasons.
In the case of communism - the idea is that everyone shares their efforts/product and currency doesn't exist. The fundamental problem is that it ignores supply and demand. Depending upon the technology and processes available to a society - there are a minimum number of metal smiths necessary to support society. There are a minimum number of waiters/waitresses, etc. If you have a bunch of actors or actresses leading to a huge surplus of entertainment... there aren't enough people taking care of the material needs of society.
This ultimately leads to the need for centralized planning and control over how many people will be performing various duties. Communism tends to break down under the effects of free will (even if everyone is legitimately working).
Capitalism - or the free market - is the idea that a person is free to create a product or service and set some metric of exchange that they will accept to render that service or part with the product.
Capitalism runs into a very simple problem in that I cannot simply make something like a computer. Resources; the equipment necessary to process materials (as well as the knowledge) are all fundamentally limited. It is possible for a single interest to form a monopoly over those resources and set exceptionally profitable exchange rates for those resources. The supply can be realistically and artificially limited.
This is especially the case when government gets involved. The reason why large corporations support lobbying efforts for environmental regulations is because those regulations prevent the upstart of new businesses that could potentially upset the market. Any corporation's manufacturing lines are easily ten years behind the most modern manufacturing processes available. New businesses are often the ones that take advantage of the latest and greatest technology across their entire line as they have no process to interrupt or work around. Because of that - even with startup costs included, they can often out compete larger industries in the most competitive markets (new technology) and establish themselves as market share leaders in those products that will often hold for two or more decades.
Unless, of course, the costs of start-up are inflated and slowed down by bureaucratic tape and regulations. Which is exactly the reason for them.
The public thinks its getting cleaner industry (when the regulation doesn't do anything but make things more expensive for start-ups), but is really just getting bound to GE or whomever's product line.
