These could be pics from any one of many crawl spaces that are inspected during the summer months here in the southeastern part of the US. This is especially true for those that have AC duct-work running through the crawl space.
The conventional way of constructing a crawl space is to provide 1 square foot of venting for every 150 square foot of crawl space and can be reduced from 1:150 to 1:1500 where a Class I vapor barrier is installed and maintained.
With the humidity levels in the southeastern US, it seems that crawl space vents can introduce much more humidity than they were intended to reduce. For this reason, there is a new thought process developing about the construction of crawl spaces in our area. The bottom line is that it may be better for them to be non-vented
A non-vented crawl space can create another concern with radon. Radon is a naturally occurring gas that comes up out of the ground and is no problem unless it’s confined and not allowed to vent, resulting in an accumulation of the gas. This can be addressed by burying perforated pipe under the sealed vapor barrier, that vents to the exterior of the house, giving the radon somewhere to go.
Instead of going into this in detail here, please see the research project that is being conducted by Advanced Energy at http://www.crawlspaces.org/