Bill James, in a recent interview, compared steroid use in baseball to abuse of the traveling rule in basketball. James, who probably aced the analogies section of his SAT, argues that it's unfair to expect the players to follow rules that are never enforced.
I don't chime in much on the PED issue, because I'm not well-versed on the subject, but James is clearly correct here. How often do you see pitchers argue that they don't get a call on a chest-high pitch, even though it is clearly a rulebook strike? How about second basemen complaining when runners slide five feet out of the baseline to take them out on a double play? Rafael Betancourt takes more than 12 seconds to throw on virtually every pitch, yet it was a national story when he was finally penalized once for doing so--by the ump calling an automatic ball. Take that, you scoundrel!
Think about the last 20 times you've watched a football game and seen a wide receiver trap (rather than catch) a pass while sliding or diving for it. What did they all have in common? The receiver acted like he caught the ball every time. Why shouldn't he? If he convinces the refs, he gains some "free" yards for his team or forces the opponents to use one of their challenges to overturn the call. If he fails, there's no loss; the team gets the same incompletion either way. Just as in many situations in sports, there's absolutely no incentive for him to play honestly.
What incentive did players have not to juice? Essentially none, except for the side effects. One of the lessons of the Freakonomics/Sabernomics era is that incentives are affecting people's decisions everywhere around us, not just in the fantasy world of Econ professors. If a player is allowed to gain a competitive advantage with no repercussions, why should we expect him not to do so?
If the players really had such easy access to PEDs in the 1990s, I'm surprised such a small fraction of them actually used. Perhaps those who chose not to considered the health costs of using steroids, but maybe they just weren't comfortable "cheating" to get ahead. I doubt the same players refuse to take out the pivot man on a double play, or occasionally fib about catching a line drive that they actually trapped. Hank Aaron once had a home run taken away because he stepped far out of the batter's box to hit it. I find it hard to believe that he only did this once in his career, but I don't see him offering to take the dubious homers off his stat sheet.
Sure, PED use is immoral. But if everyone else at your company was bending the rules to get ahead, and you knew you would not be punished for joining them, would you really sit back and get passed over for promotion after promotion? If so, you're probably a better person than me, but you might well be the lowest paid employee at your office. It's just one of the many trade-offs we all encounter in life.