For starters, there are a number of recent Supreme Court decisions (interpreting the Federal Arbitration Act) that allow ToS to prevent consumers from suing as a class [1, 2], thereby ensuring disparate legal resources in favor of a corporation.
Generally speaking, the difficulty in bringing criminal cases against employees of corporations is convincing a court to pierce the corporate veil.
Unfortunately, this presents a catch-22. In order to prosecute an individual for corporate actions, one typically needs to prove the individual engaged in fraud or knowingly illegal actions (circumstances that justify piercing). However, if proved, one is unable to also sue the corporation (as you just argued the individual was acting against corporate interests and/or without corporate knowledge).
Furthermore, and I hope a lawyer corrects me if I'm wrong, criminal law requires much more stringent tests to prove guilty intent. In nebulous corporate power structures (and employing very expensive lawyers to design systems to shield themselves from exposing this proof), this is usually impossible.
E.g. criminal prosecutions over the housing crisis
[1] AT&T Mobility LLC v. Concepcion (2011), https://en.wikipedia.org/wiki/AT%26T_Mobility_LLC_v._Concepc...
[2] American Express v. Italian Colors (2013), http://www.scotusblog.com/2013/06/details-american-express-v...