Most are, due to the limited availability of microwaves in India, although this has changed in urban centers now and I have seen microwave safe plastic ones as well. Generally you (or your chef!) would pack the food hot in these metal containers and then place the entire tiffin inside an insulated vacuum flask like container so that it stays warm till it reaches you.

Here's an Indian site that is selling a microwave safe tiffin set with a built in heating mechanism for under $10. I just googled for it, so I can't vouch for the quality though. http://www.rdsons.com/prods/kitchen_apps/elictrik_tiffin.htm...

Near the villages and country side most of it metal. Most due to high durability.

But in Metro's Plastic is pretty famous and is widely used. Its in our culture to carry tasty food cooked by moms to schools/offices. But it seems like that culture is changing big time. McDonalds et al, have started offering good enough meals for 40 rupees onwards(less than $1 approx).

Having said that, 40 rupees very unaffordable for a lunch meal. Even for a software engineer. Dining in all these McDonalds sort of restaurants is considered as for rich people.

Yeah I almost clicked buy until I thought "How will I reheat these, microwaves will not like these!"

So now do you understand why tiffin boxes are made of metal. Not that microwaves can't work with plastics or all sorts of plastics.

But because most people in India can't afford to buy a microwave at the first place.

We have plastic bowls for use in my office, and a micro. As do most of the other offices - I am in Mumbai, and a micro isn't that hard to afford for the middle class and many firms.

That said, there are a lot of other people who eat their food cold. This is India, so for whatever N=true, N'=true