I wonder how you came to this conclusion. In fact, farming in India is very fragmented. Lot of farmers or people in rural areas own very small parcels of land and work on them. Yes, there are people or families which own large pieces of agricultural land, but not in the numbers that you seem to imply.
Also, lack of manpower for working on farms is a very real problem in India. Farming jobs still exist at a big scale in India because we don't have mechanization like western countries(Again because of fragmentation of farms). People are not willing to "slave around" in farms anymore because they get subsidies from government i.e. food at very low cost for people below BPL. And it is very easy to get a BPL card if you live in rural area. This comes from someone(me) who has worked and been around farms and is still involved in farming though not directly on a day to day basis.