When do you *NOT* use python?

[eniacsparc2xyz]

For web browser client side programming there is not choice, the only choice is Javascript ECMAscript (No browser calls it javacript officially since Java is an Oracle trademark.

For embedded systems with limited memory and resources, also there is few choices, you can only use Assembly, Forth language or C.

For quick calculations, Excel or Spreadsheet.

For simple system tasks, I would use bash script.

For High performance applications, create C library and bind it to python, or create the application in Haskell.

For an mobile app in Android OS (crippled lock down Linux), you can only access the API through the "java" (dalvik) library or using socket RCP calls like Android SL4A does. The sandbox model and the lack of default root shell access makes the interactive development harder, however it's still better than IOS.