Why is it so expensive to deploy a container to the cloud?

I have a variety of hobby projects that I deploy as Docker images to avoid vendor lock-in. I'd prefer to deploy these to a managed platform because I don't want to worry about OS updates, monitoring, failover, etc.

It seems like this should be extremely cheap to host: a provider could slice up a $5 VPS to host 10 services, selling for somewhere between $0.50 - $2.00 per service after overhead. Yet every time I price out cloud providers with managed Docker platforms the cost is substantially more.

Heroku's free tier only covers a single daemon or a handful of web services, and jumps to $7/service minimum after that. That gets expensive quickly.

AWS ElasticBeanstalk is ~$25 after you use up the free year, and AppEngine Flexible Environments looks similar.

I see a handful of other providers I've never heard of and am not sure I can trust.

Where are the cheap Docker hosts? Why can't I rent a fraction of a VPS instead of a whole one?