Tech companies typically do increase your salary if you move to a higher CoL area.
The buyer (Facebook) may not be playing all their cards. They may very well intend to reduce SF employee headcount, but want to experiment, and so saying otherwise will allow them to do it in a slow, controlled manner.
I personally have no problem with it and did just that at least once, but after returning I asked around and most if not all of my friends and family would not do the same even for - and this was especially shocking to me - 4x the salary.
Apparently flexibility is rare and sought after.
I got an offer for an on-site job in London the other day, that would technically be ~1.5x salary boost - and ~5x the salary I had the last time I worked for a local company. But after subtracting out the costs of living, it turned out it would be effectively a 3x salary decrease, and at the same time a significant degradation in the standards of living. Turns out, London isn't a particularly friendly place for a couple with a toddler to move to.
In terms of what I could nominally save every month the difference was enormous.
But yeah, with a child on board I would definitely have to get something larger paying somewhere in the order of 25-35% of my salary. But that's just CHF = PLN again, so no increase here.
What do you mean by 3x decrease? X/3 ?
Later I asked one of them if they wanted to know the salary range difference preferred not to think about it
Forced analogy time: It's like if I decide I'll only buy peaches from the organic farm down the road. They charge $20/lb. I calculate that I get $21/lb worth of utility. The Farmer is happy.
A few years later I decide that purchasing organic peaches online for $15/lb fits the bill, and utility dropped slightly to $19/lb but still better in comparison. The farmer is no longer happy.