It's the same people making or not both the Laws helping specific really wealthy companies who are known to provide gold-plated "opportunities" to friendly retired politicians and the Laws that would stop such obvious conflicts of interest, so of course they don't make the latter and thus it's perfectly legal to, after favoring certain companies and industries as a politician, retire from politics and go get paid a couple million a year from some company that the laws you made and measures you enacted helped.

This is why Democracy is supposed to have 3 independent pillars - Politics, the Press and the Judiciary - which watch over and keep each other in check: if the Political branch allows most forms of what in practice is corruption to be legal, the Press is suppose to hammer them for it.

Sadly, the Press is a lot less independent nowadays, ever since the same people who own the companies that benefit from "friendly" politician lawmaking bought most of the Press, plus specifically for the EU, its politics naturally get way less coverage than national politics in all EU countries (plus EU structures like the EU Commission are far more opaque), so naturally under such reduced visibility and understanding the crooks that manage to get themselves into lawmaking and executive positions in the EU get away with far more funny business than they would otherwise.

My own feeling is that if measured in terms of the amount of negative impact on EU nations and citizens, what people would consider to be corruption (so, all situations where politicians benefit certain economic interest in the expectation that they themselves will personally financially gain from having done so, even if they're actually legal), the EU structures are probably the most corrupt political structure in Europe, not because of having more corrupt people in it that elsewhere but because the measures enacted there have the most impact of all hence in that process benefiting certain interests by adding costs or limiting freedoms of others causes much more damage that it would if it was done at a local or even national level - a single corrupt EU Commissioner can cause far more damage than a single corrupt government minister in an EU nation.