I live and work in Australia where the market for engineers is quite small and all of the medium to large companies almost have a revolving door in that I've worked for a company, left to work for a different 2 companies and then come back to the first then left and contracted to the first many times and now contract for dozens of different companies.
It's quite common now for a lot companies to work only with a core of permanent engineers and a lot of contractors that come and go.
Basically I don't think we are valued very highly but we're trusted to be ethical and do the right thing. This while having ups and downs is at least in line with capitalist ideals where as what's going on over yonder is criminal and very anticompetitive.
Sure, this does not just apply to EE alone. Employee in almost any sovereign intelligence-related, or defense related industries, or any securities related will have limited choices when it comes to moving to a different company - as "security risks" is always a factor involved. So, EE hold the secret knowledge of the propretary and technical knowledge, they are similarly treasured for the protection of these knowhow. Many of us may not like it, but it is (and always will be) a fact of life - that these anticompetitve measure exists, from both party: will you trust to employ someone technically capable in a previous company that he will not siphon away your current technical strength to his previous company, and vice versa?
This whole thing reminds me of a line from Casablanca that went something like "I'm shocked, SHOCKED I tell you, that there's actually gambling going on in this casino!" I remember hearing about these agreements back in the late '70's when I was working in the computer peripherals industry, I believe the organization that I was aware of promoting this was WEMA which I think became AEA, I then recall coming into a related company in the early 80's as a consultant and hearing myself the head of HR calling the other firms in the organization on a regular basis and going down through the list, how much are you paying for an assembler, tech, MTS etc. What makes this so hilarious that this FINALLY came to someone's attention and everyone's acting surprised, when it's the federal government ITSELF that withdrew "safe harbor" from the tax laws that apply to the tech industry and forced us through that section 1706 fiasco (which of course is STILL in effect), which basically says if you work in ANY industry you can of course "hang up your own shingle" and become a consultant, unless of course it's the COMPUTER industry, in which case you're singled out for "special audit" and potential recalculation of your tax status with ruinous penalties and fees as a "general employee" of your client if the IRS happens to "determine" you don't meet their criteria. And NOW there's suddenly CONCERN that the "technical class" is discriminated against?? You're kidding aren't you?