Common practice for sewer systems using septic tanks, rather than a secondary wastewater treatment plant. Same practice is used in much of rural US.
What?
I have lived in rural America for over 40 years with both older gravity type septic systems and more modern pumped systems. No one puts TP in a separate container. All our systems can handle toilet paper.
What you have in the 3rd world is gravity based cesspit systems. Even modern toilets cannot handle paper in that instance.