These construction workers come from India, Pakistan, and Bangladesh and work in oil rich countries. They make their own food for secveral reasons. Either their traditional types of food are not available nearby the construction site, and/or it can be expensive. So, they save time and monety by using whatever is available to make home-made food.

Regarding paint ..etc. most of these workers are not undeucated and they are not really concerned with such details. A good wash of the barrel is enough for them . They can be very skilled in saving time and money, or managing to do the near-impossible, but safety isn't always high in their list.

Having said that, I think the barrel has been used for so many years and all paint is already gone by that time. I have seen these barrels during construction of my house and several relatives' houses. The barrels are usually used to store water for the construction and they are rusty inside and out.