Wow! So if you can't prove they are explicitly colluding then its OK? Doesn't this mean they can get away with it by, for example, not having anything written

Wow! So if you can't prove they are explicitly colluding then its OK? Doesn't this mean they can get away with it by, for example, not having anything written down or recorded? I assume this applies to all industries E.g. the health Industry? I'm getting more and more worried about the US.