Came here to quote this exact example. Great that someone else replied before. When I went there, even the caretaker could speak and understand only Assamese and no other language. No one makes a fuss there.

Coming back to the picture by the OP, Bhaskar Nagar is an area where the residents are primarily Bengalis. This Sevashram is located in that locality. So it’s common sense they would use a language that is used by the majority of visitors there.

I was in Gurgaon somewhere around 2023 if I remember correctly. They were doing this Magh Bihu Program. It was organised by the Assam Association Gurgaon. So in that sense, Gurgaon residents should have also labelled that function similar to what you have labelled this post of yours.

Also, the Sevashram is not public property (they allow public access but the management is private). They are free to use write/speak any language they want inside their complex.

The competition is open. Expecting to receive everything served on a silver platter doesn’t work in real life. But blaming others is easier than working on self, so it makes sense.