food consumable, like drinks in glass jars, or food in cans, not returning an empty jar or can

I assume that is intentional. 
This game should be called "2 days to starve". 
You find a half kilo / a pond canned food can and that sustains you for 15 minutes. You need 40 of those to live one day. So you need to eat 20 kg of food a day. Same with water. You need to eat and drink more than it is possible. 
Not only is it unrealistic but it is boring to play eating simulator. 
A canned foor can should sustain you for one day , easily. And it used to be more like that in A10-ish canned food can gave you 50-90 food, now it gives 10. A pound of canned meat sustains you less than boiled egg. Canned food used to highest tier food. For a little while you could even craft canned food when game has smell - mechanics; if you carried un-canned food, zombies and animals would smell you and detect you from from long distance. So when you killed an animal and got fresh meat you were at risk. That was interesting and required you to play smart. Then they removed the smell mechanics. The Heat Map was interesting years ago, all changes to enviroment, cutting trees & building attacked zombies. Then they nerfed that to just to when you are near running forge + dynamite + power tools. Back in A12-ish shooting attarcted zombies from like a mile. 

I like the they put the recipe books back into the game. But they have removed so many good game featres that this game feed a bit of a mess. You used to get empty cans from canned food, and you could fill the empty can from water source to get Can of dirty water. And you could then boil that water in campfile WITHOUT cooking pan. That made sense and nice game mechanics to learn. Then they removed ability to fill cans and to cook them. 

Game had "Burned meat" which you could cook in camp fire without cooking pan. I think it now needs cooking pan. So there is no point of having that item in the  game. 

Empty jar and empty can were the main survival items in the early game. Having removed those there is again so much less "survival" features left in the game. 

Too much reality makes poor playablily. But they removed stuff that both made sense and was nice and interesting game mechanics. Those examples are just few of the stuff the game has lost since they tried change his to console game. 

 

Jars and cans have been removed from the game.