The simple answer is most people that use an electronic device -- Tor or otherwise -- have no idea what they are doing. Because Tor is advertised as extremely safe, they think they are safe. Anyone wanting an interesting stream of data just has to operate as many exit nodes as their budget can handle.
Additionally, I'd assume that most organizations that are able to run or back-door a large percentage of TOR exit nodes are also able to mint SSL certificates under keys that most browsers would accept as legitimate.
The simple answer is most people that use an electronic device -- Tor or otherwise -- have no idea what they are doing. Because Tor is advertised as extremely safe, they think they are safe. Anyone wanting an interesting stream of data just has to operate as many exit nodes as their budget can handle.