Earlier quoted context omitted.
The company you work for almost always has more power in negotiations than you do. (For some hypothetical "you".) The bigger the company is, the more power they have typically. If you want to make more money or get better benefits or otherwise negotiate a better contract, you need more leverage. Unionizing is one way to gain more negotiation power by negotiating together with your co-workers instead of individually.…
A lot of HN repliers think that they , out of thousands of other employees, are that One Captain Of Industry that has sufficient bargaining and negotiating power to stand toe to toe with a huge employer. And therefore, a union could never help tech employees as a class.
Eg, that they necessitated so called "rubber rooms" like these in the NYC public schools, where teachers got paid to do nothing while waiting on arbitration.