"Robust" has different meanings. I think the OP is equating robust with strongly typed and compiled. I have found well written PHP code requires very little

"Robust" has different meanings. I think the OP is equating robust with strongly typed and compiled. I have found well written PHP code requires very little unplanned maintenance. When I package the application in a docker container along with its dependencies and a webserver (nginx), I find that I can run a PHP application for years without having to worry about it. In this sense, PHP code can be very robust in the sense that there are little surprises once the application goes into production. The PHP ecosystem is very mature.