If the problem would be just employees "shopping around" that would not explain, why wages are not rising. If they would shop around, wages would also rise, even when they are only marginal interested in wages ... (show me 3 employees that are not interested in wages)
Tech wages are very inflated as is, expecting them to rise is pretty silly.
When I was looking for my current job, I forgot to even ask about wages. So maybe what they gave me in pay is "flat" from five years ago, but it's still twice what any of my friends my age are making, while they have degrees and I do not.
I was only reacting on the argument was made by the OP, that is not logical in my opinion.
I do not know about tech wages in the US. In Germany, the tech wages are not inflated, at least not in my opinion. The normal tech wages have risen maybe 3-5% per year the last few years in Germany (I don't call this inflated) and the years before it was even less.
In the same time, the wages for top-managers have risen maybe 10-15% per year and are since decades incredible high above the wages of "tech wages" (the difference is climbing and climbing). I call that inflated.
Your statement of course is more logical than that of the OP.
Developer wages in the US average around €62k, about 20 higher than in Germany, while the US has roughly 30% lower cost of living.
Also, in Germany you're at a 40% income tax rate at €43k, while in the US at €62k you're only taxed at 25%.
Sure, that 40% income tax rate gets you universal healthcare, while in the US we're paying ~6,339.71 Euros a year to insure a family of four. But I think even accounting that, wages are much higher in the US.