[KnightWhoSaysNi]

Several PaaSes support PHP, too, so no major difference there. In a VPS environment, however, setting up PHP doesn't require anything - it works right out of the box - whereas Django and Flask require more packages to be installed /and/ require some lines of server configuration and a script that loads your framework.

[mtogo]

In a VPS environment, however, setting up PHP doesn't require anything - it works right out of the box

Well, you do need to install the AMP part. Since you're installing and configuring three components, why not install and configure different ones? It's not more or less work either way.

If you're talking about AMI/StackScript-style pre-built VPSes, there are plenty for various Ruby, Python, and Node stacks as well as PHP.