For one, water doesn't control all types of fires (ABC) so one size doesn't fit all- especially in all the diverse things in a machine shed or livestock barn. Expense and the maintenance required are a couple other things to consider. To me it would be like someone installing a halon system on their backhoe. I guess if you have the will and the money it can be done.
Another consideration, to be automatic, there has to be a way to activate the system - either through smoke detectors or heat detectors wired up to a processor via flow switches to activate the whole operation. A jockey pump is used to maintain the water pressure in the system when the main fire pump isn't running. That brings the 55 to 60 psi city water up to the required 105 psi plus water pressure. So having a good supply of water at the required static pressure is another consideration. Then there are tamper switches to alert and ensure the system hasn't been turned off and is functional. The "dry systems" I'm familiar with use an on-demand air compressor that maintains about 25-35 psi in the system. I do a monthly churn test and every 6 months a licensed plumber trained in fire systems (and a JD-50 owner) checks the flow and tamper switches.