It appears PRISM refers to a system by which the US government demands information from companies, and not a back door for direct government access to the companies' servers.

Nonetheless, many companies went out of their way to make it easier to give the data to the government.

The US can do plenty to spy on Internet traffic to these companies even without their cooperation.

The government should be able to get information from individuals and companies for investigations. That part of things is not what's wrong. What is wrong is that Internet sites collect so much information about nearly everyone, which can then be handed over to the US government for an investigation of "terrorist suspects" such as dissidents or whistleblowers.