Priceless for them: they were on a higher salary for some time AND now have a great package in their account.

May I guess that you are new in Switzerland? You don't get "great packages", you simply get fired here...

You negotiate the package when you join, at least for senior jobs

I always thought salary details were within the "secret umbrella" that they have here about aspects of commercial life?
I have certainly worked for companies here that had revealing salary details as a disciplinary offence in the employment contract.

A "mate" works at a company that has a high-tech multi-functional printer/scanner/color-copier with various network functions. If you scan a document, it ends up in a network folder and you have to retrieve it yourself and delete it there. Let me put it this way: HR people are apparently not the biggest IT talents and the mate has discovered more than once some fairly private information when he was searching through the network folder for his scans. A year ago some of his colleagues found a company-wide salary list there...

Best answer in the thread I think was the one which referred to "my salary is roughly xyz incl. bonus, and on top is car, etc.". The bonus makes it sufficiently vague and leaves room for stretching the truth (assume in the quote that your bonus payout is 200% for instance...). In some countries/companies HR will ask for copies of current package though (e.g. options/shares) so there's a risk there.

One could also be super honest: "I'm not going to divulge my current package because it'll just result in getting an offer of "current package +5%", but I am looking for xyz

In my company it was even more blatant. Some fool in HR printed out some emails without checking that they had selected the right network printer and it came out on our printer rather than their's. When she realised her mistake she came over red-faced and asked for those documents wanting to shred them. We were happy to comply but didn't tell her we'd had enough time to run them through the photocopier first.

On another occasion but by the same method I came by a pretty incriminating mail that's maybe not bad enough to be worth whistelblowing over but could form a nice piece if I ever write my memoirs. I don't know if the HR person knows or if I'm just imagining it but she's been much more cooperative since than she was before.

And then those exec's who are preaching need to keep salary increases low due to economic reasons etc etc all of a sudden look like bastards: fat increases, high bonuses, options/shares, etc

A friend of mine recently got a 1% salary increase (net of tax increase and inflation it was actually a decrease). Justification was that she was already at 129% of mean for her job and HR has 130% of maximum so higher than 1% is not possible. Never mind that she works in finance and could see her boss just got a 50k euro stock award.

Ultimately one can only treat companies the same way companies treat people: with complete and utter contempt.