Thank you for the clarification.

I can see how areas set aside for growing food can be tagged as orchards or farmland, especially when the land is plowed or has fruit trees on it. 

Allotments are communal places where multiple families may own or rent a plot to grow their food. Private backyards are not that. That said, I do see the need to distinguish these areas from large fields where farmers use their tractors etc. 

Would it make sense to you to retag the landuse=allotments that are not actually allotments to leisure=garden + access=private with a relevant garden:type=vegetable_garden? The last tag is currently undocumented, but is already in use according to Taginfo and seems to fit your description well.

Best regards,

Casper