Amazon has invested an insane amount of money into the recruiting/interviewing/hiring process. It has always been the Amazon mindset that workers are replaceable, and they have built their entire business on the operational model of hiring quickly, draining people of all their productive output, firing them (or pushing them so hard they quit on their own), and quickly hiring people to replace them.

When you have that mindset and investment in those areas, and especially when talking about positions that require relatively little training investment, I wouldn't be surprised if it is cheaper.

I think Amazon is reaching a point where the incoming pipeline of workers is drying up, though, and Amazon execs are apparently clueless on what to do next. It's really a situation where Amazon squeezed its workforce so hard in search of short term results, and now is reaping the long term results of a workforce that hates the company. Ironic, since one of Amazon's precious leadership principles is specifically to not do that.

All of this also applies to the corporate workforce, too, btw. There's an insane amount of attrition right now and nobody qualified wants to work at Amazon, even with the 200k+ offered salaries. It's not just a money issue, but a reputation/culture issue, and Amazon organizationally doesn't know how to solve those types of issues.