Iran is a very underrated country. Many people think that Iran is a poor undeveloped country but that's not reality. We import many foods and medicines from Iran and I also know that Iran has great scientists.
As they say: necessity is the mother of invention. For example the more US sanctioned Iran, the more Iranians had to move toward self reliance. This is why Iran is so advanced in many sciences either on par with the rest of the world or ahead (Nano technology, stem cell research, medical engineering, space technology, ...).
I don't know what you will do with 50 kg of rice, unless you are an industrial business owner. We normally buy 1 or 2 kg.
It comes down to the cuisine. In our neck of the woods, most of the food are with rice (like rise and stew, kabab and rice) so it is consumed a lot and when you are a family of 3/4 you buy big bags and store them easily. Usually we buy 10 kg bags.
BTW Wikipedia lists a lot of our food in case anyone is interested:
https://en.wikipedia.org/wiki/Iranian_cuisine it also has my favorite "tahdig"
I wish that the governments of most developing countries will adopt this measures like Iran, to subsidize basic food items like Rice, other locally grown grains, meat and cooking oil.
Although it has many advantages but also it has some disadvantages as well so I wouldn't be hasty in making such decisions. I can think of two main ones:
First is that it grows the government expenditure, so they'll need more budget and if they can't find additional revenues to cover that up they'll face a big deficit. And we know when governments face budget deficit, the first thing they turn to is the easiest solution which is to print money. Printing money causes inflation then everyone loses!
The other disadvantage is that over time it can create a price difference between the country paying those subsidies and its neighbors that don't. That makes smuggling very profitable that it becomes appealing despite being illegal and damaging. And then if that is not managed properly, it can turn into a big issue. I can mention two examples of such issues: with cooking oil and with petrol.
As you may recall a couple of years ago after Russian invasion of Ukraine the cooking oil price went to the moon globally. In Iran due to these subsidies the price remained low but not elsewhere. All of a sudden massive amounts of cooking oil were being smuggled out of the country that it turned it into a national security threat. It was managed rather well by changing the way subsidy was paid (paid to the customer instead of the producer).
But the issue with petrol/gasoline is not yet solved. Price still remains super low at 2 cents ($0.02) per liter! While it is a lot higher in Iran's neighboring countries like $1.22 in Turkey, $0.9 in Pakistan, $0.68 in UAE, etc. It is obvious that it will be smuggled to these places because it is super profitable to do so. That's like 6000% profit to smuggle it to Turkey
Consequently Iran is now facing a petrol shortage, and the problem hasn't been solved yet...
The point is, it is not always a good decision to give subsidies. At least not in the long run.