When people refer to humans as "sheep," it frequently sets my neck hair on edge. Mostly because I'm a speciesist, but also because people lump together a wide variety of disparate behaviors to imply that people "mindlessly" follow social norms. If you falsely establish that people have no will of their own, then it seems harmless to push (or nudge) them around. However, people frequently mimic the behaviors of others for laudatory reasons.
A loud talker might moderate his voice to set someone at ease. You might refrain from wearing certain types of clothing for the same reason.
You might drive on the right side of the road to avoid blood guilt.
You might watch the TV shows your friend likes because you enjoy the camaraderie of a shared culture.
There are many reasons why "sheepish" behavior is distinctly human.
Minnesota experimented to determine what increases tax compliance. Groups of tax payers were sent two different informative messages. One message described the beneficial things the tax money would be spent on: education, health care, law enforcement, etc. Not too surprisingly this strategy didn't work. You probably fall into one of two camps: (i) you think the government spends money wisely, or (ii) you think the government is willing to pretend it does in order to get more of your money.
The second message informed people that "Audits by the Internal Revenue Service show that people who file tax returns report correctly and pay voluntarily 93 percent of the income taxes they owe." The fact that the second message worked is often chalked up to fact that people follow social norms. But what does this mean? When you learn that more people pay taxes than you expected, you might pay your taxes because you are a mindless follower, or you might adhere to a certain notion of fairness. If other people pay their taxes, you might not want to be a free rider. However, a high level of tax compliance doesn't mean that people accept that the tax is just. People might pay a tax out of fairness even if the tax itself is unfair.
Imagine a state of anarchy (a lack of government not a house full of boys). An evil genius announces that he will impose a sucker tax. Everyone will be taxed ten dollars, and the proceeds will be redistributed back to all the citizens in equal shares without reference to who paid the tax. In a certain sense, this tax maximizes unfairness. It serves no other purpose than to punish people in direct proportion to how much of the tax they paid. To make tax compliers feel even more ridiculous, the evil genius announces that he will make no effort to punish "tax cheats." A fair outcome of the game requires that there be no suckers. This will occur if everyone evades the tax. However, it will also occur if everyone pays the tax. Under this scenario, you probably wouldn't pay the tax (even if you believed in fairness) because you would assume that no one else was going to pay the tax.
Now imagine that the evil genius announces that unless everyone pays the tax one person will be punished. The "everyone evades the tax" strategy is no longer socially optimal. What to do? You then learn that everyone else is paying the tax because they think everyone else is paying the tax. With this new information, people motivated by fairness will pay the tax. Tax compliance is 100 percent even though everyone despises the tax.
Compliance does not mean consent.
P.S. I'm not fanatically against sheep imagery; some of my best friends use it.