1) For a long time, there was no "institutional" left in the United States; so in the US - liberalism was seen as the "left". This is slowly changing now...
2) The tech crowd wants really to believe to be progressive (because they work on "progressive" technologies); but in fact, I never saw so many real life liberals like among tech workers.
It's an interesting combination that doesn't fit super-well into America's dominant left-right political axis.
https://en.wikipedia.org/wiki/Political_spectrum#Greenberg_a...
Eg. Support gay rights and environmental causes, but don't really give a shit about poor people.
Liberals are often right wing parties in other countries. Basically you have a scale from socialism where everything in your life is dictated by social contracts to liberalism where almost nothing in your life is dictated by social contracts. The left in the US calling themselves liberals is kinda like the north korea calling themselves "democratic people's republicc". Their only liberal agenda is freedom from the Christian social contract.