The linked documentation could be more clear, but it is not correct to say that "autoscaled" instances are "up constantly costing you $". You linked to the "Instance State" section, and it is saying that "autoscaled" instances will only ever show as being in the "running" state (vs the "stopped" state possible for "manual" or "basic" scaling). This is because "autoscaled" instances are shut down after some time (if no requests come in), not that the instances are running 24/7.
The linked documentation could be more clear, but it is not correct to say that "autoscaled" instances are "up constantly costing you $". You linked to the "Instance State" section, and it is saying that "autoscaled" instances will only ever show as being in the "running" state (vs the "stopped" state possible for "manual" or "basic" scaling). This is because "autoscaled" instances are shut down after some time (if no requests come in), not that the instances are running 24/7.
I have to agree with @msl00 here! It's unclear and AFAIK AppEngine can NOT auto-scale to 0!
App engine standard environment can scale down to zero. I'm paying zero for for my hobby project. cloud.google.com/appengine/docs/th...