If I'm in debt to somebody 10.000, he owns me. If I'm in debt 10.000.000, I own him. Huge fines for behemoths will always be negotiated.

Nevertheless, it's a strong incentive for even the biggest companies to follow the law. EU has the capability and desire to enforce huge fines to make sure data protection laws are obeyed.

Fines in antitrust cases can already be huge so I would doubt that those fines could be gamed if regulators take it seriously. The alternative to paying a fine is being banned from the market, which for the EU is a big deal.

They actually do get fined huge sums, and they do pay up. To them it is just the cost of doing business.

Facebook getting fined for privacy violations:

http://www.bbc.com/news/business-39958630