While there are certainly more puritanical abstainers in US vs EU, as alluded to corporate policies are more about liability issues; employers could be liable for any issues caused by serving alcohol to an employee. I'm sure that's what drives our policy, since alcohol consumption is allowed off-site.

The self-imposed non-consumption of alcohol during work hours also has to do with competitive pressures. Those of us with such jobs can't afford to waste an afternoon drunk, or worse, make a big mistake due to being impaired. Just like what's happening to smoking in the EU professional class, that will curtail EU work drinking more than any taboos.