> A lot of AWS's managed services are just off the shelf open source projects on the backend.

Amazon employee here. Amazon offers two different types of service. For a service like Amazon RDS then yes it is the standard open source project hosted and managed by AWS. The value add is that you don't have to administrate and back it up, etc.

For something like Amazon Aurora its a different story. Aurora is API compatible with MySQL and Postgres but it is designed internally to work quite differently, really designed for the cloud first. And the result is its up to 5x faster than the standard open source software and just better than the open source version in many ways.

Both as a former customer of AWS and now as an engineer at AWS I have always preferred the from scratch implementations by AWS over the hosted open source versions. I'd rather not use a forked version of open source. I'd rather use something built by AWS engineers from the ground up

> For something like Amazon Aurora its a different story. Aurora is API compatible with MySQL and Postgres but it is designed internally to work quite differently, really designed for the cloud first. And the result is its up to 5x faster than the standard open source software and just better than the open source version in many ways.

It's also noticably slower than plain PG in other cases.

As the cloud often is.

Why doesn't Amazon just pay mongodb? If you you hired some employees from mongo you would have to pay money.

Predictability: who's to say what MongoDB will decide in the future e.g. ask for more money and/or charge per vCPU + memory. Employing developers directly, on the other hand: here's an offer and vesting schedule - they know exactly how much they will spend for 3+ years, and get to control the roadmap.

Because Amazon is all about squeezing every penny out of their supply chain.