Unless I've misunderstood what the fine was for. Fining a private business €2.4bn for promoting its own affiliates over other networks, how is that in any way an abnormal business practice? I'm not trying to be controversial, I just don't understand how that warrants such a hefty fine.
It's because there are additional regulatory requirements on businesses that have disproportionate market influence.
Promoting your own services in general is fine. But when a huge, huge majority of the market uses your service for discovery, your decision to promote your own services over competitors' damages competition in the market — users end up with less choice in practice, even though they could theoretically switch to another service.
Those rules exist to try and prevent this sort of abuse happening.
According to the press release, Google went into the product comparison sector and took about 80% of the pie without competing with other product comparison engines, instead they just used their dominant position in search.
If they had competed and won this share fairly, they wouldn't get a fine.
Remember that EU, during these years was consistently the largest, or the second largest, depending on year, economy of the world, so this 80% is huge and justifies the size of the fine.
