Furthermore, just because someone has a managed k8s doesn't make it less lock-in or less work. With AWS you don't need to use a cluster of anything. With k8s you are signing yourself up to tons of complex services and specific design and operation paradigms. With AWS you have no such inherent restrictions.
K8s is inherently more complex and difficult to use than AWS services, which aren't even a good comparison because they are so simple by comparison.
This is, in my experience, quite a false statement when talking about AWS. You are either a (team of) 10x engineer(s) capable of anything or as you grow in people and services you will need to use a good chunk of your developer time managing AWS, or hire a dedicated person (sysadmin).
Just because businesses hire dedicated backed people doesn't mean they actually need to, they just feel better about it when they do, because that's how it was always done before.
And since the OP was talking about Kubernetes, and you're talking about "lock-in", another reason I love AWS is it is not a lock-in device. I can use any service of AWS's by itself, without being forced to use anything else or do something in a proprietary way. All the interfaces are a command-line or REST API with JSON data formats. They are all designed to operate by themselves, so you can provide replacement components at any time, hosted anywhere.
On the other hand, you can't just use one part of K8s, because you have to at least set up and manage an entire cluster first. And there's dozens of services K8s simply does not have, and other hosting providers don't have.