Labor is one of the most expensive parts of running a business. So just doing the math of, if we spend X amount of money on robots and can layoff Y amount of people then it's a net gain. Especially if a single machine can replace multiple people.

Also fixed equipment / robots do not ramp up when the demand increases.

On the other hand you can always hire more People to sort more packages. You don’t even need a building, a tent would suffice.

What these companies do is conceptually very simple. Basically sortation of items at different granularities and locations. Not comparable with manufacturing companies.

Humans are cheaper than robots too...

Only sometimes and costs change over time. The first robot is almost always more expensive than a human, but the second robot comes after the design is done and so it generally cheaper than the human (accountants will figure out how to amortize these costs and thus give us a better picture of costs.)

Robots also get cheaper over time because we learn. You can buy many parts in bulk including computer libraries to control them. You can find many people who know best practices who will not make some of the early mistakes that cost money.

How much cheaper? You can hardly get humans to work two shifts a day, let alone three.

In China, yes, but not here.

I've picked orders. If I have to touch your purchase for 20 seconds it is a very long time. There are 180 chunks of 20 seconds in an hour. If the pay is $45 per hour it would cost 25 cents.

It is strange how this isn't obvious