These 2 industries have the worst benefits, and that's not going to change anytime soon

The retail and restaurant industries have the worst worker benefits in America.

A Glassdoor study published Thursday showed that both were bottom ranked. Tech and finance took the top two spots.

The job listings and ratings site studied 470,000 benefit reviews it received between June 2014 and last September to draw these conclusions.

"I don't believe that the benefit packages in retail and restaurants are going to improve any time soon," Glassdoor chief economist Andrew Chamberlain told Business Insider.

Chamberlain said it's depressing that even when benefits are available, workers rate them poorly. Two exceptions are Trader Joe's and Costco, he said, which are famous for their decent benefit packages.

For the top of the list - Wall Street and Silicon Valley - the single biggest driver of better benefits is bargaining power, for fairly obvious reasons.

Chamberlain notes that the majority of workers in both industries are highly educated, super-skilled and in high demand. And so, it's easier for them to get the perks they want.

But to really understand why retail and restaurant benefits suck, it's best to look at the manufacturing sector. It ranked third on Glassdoor's list, even after the sharp recession that the industry went through over the last couple of months.

That's because manufacturing workers usually have strong unions. "If there's anything a union is good at, it's negotiating a great benefit package for their workers," Chamberlain said.

"My best advice is if you want to be in an industry with great benefits, you've got to either find a way to get organized and be part of the union, or you can get yourself into a tight labor market," he said.