Where's the wild beer?

Something that crops up occasionally is people mistakenly claiming beer can be made by adding cereal grains to water. The latest example of this was from an article on psychedelic pints, which may perhaps explain some of the outlandish claims made:

It is of course nonsense you can make beer by throwing grains into water. So maltsters and brewers can rest easy in their beds! You might perhaps get the grain to germinate, so at one point it will in effect be green malt, but even mixing green malt with water won't give you beer. You might be able to get a mouldy mess, but I shudder to think what state the water would have to be in to make this safer to drink. 

It has occurred to me that if some sort of primitive beer is this easy to make then why don't we see it naturally forming on a regular basis? If ancients could make beer by simply getting wild grains they'd picked wet then surely now grains are farmed on an industrial scale shouldn't it be happening all the time? When barley fields are flattened after heavy storms shouldn't there be reports of beer puddles forming? Or if a grain silo or lorry has a leaky roof shouldn't spontaneous outbreaks of brewing happen? Come to think of it if it was that bleedin' easy why don't teenagers desperate to get hold of some alcohol mix wholemeal flour and water a few days before parties?

Making alcoholic drinks from sugary fruit is relatively simply, and I have seen reports of animals getting drunk on rotting fruit so perhaps naturally created 'wild' wine does exist. Turning starchy grains into something alcoholic is far more complicated though (that whole malting and brewing process) and it is human ingenuity and our dedication to getting off our heads that we have to thank for beer.