You already said it, not all friendly matches end in a draw, like over here in africa, Nigeria played against Ghana today in a friendly, and the game ended in a score of 2:1 in favor of Nigeria, it's actally the first time the Nigerian team are beating the Ghanaian team in a friendly encounter since 2006, I was actually going to bet on this match but I wasn't really sure what the outcome would be, so, I simply didn't bother betting on the game.

So, in all honesty, I believe you were simply not lucky though, and thinking on what you said about strong team not playing with seriousness in friendly matches, i personally think it all depends on what is at stack, what are the playing the frendly for, are they playing to qualify for any major game? Ot tournament?, or are they just playing to keep fit and so on?
If they are playing to qualify for any major game, or tournament, then expect the team to be on their toes and play with all seriousness, but if they are just playing the friendlies to keep fit, then I think it's easy to know why they won't play too seriously in the game.