A transportation subsidy might be local (maybe - interstates are national, not local), but farm subsidies end up being distributed nationally since they basically just mean that certain types of food are cheaper than they otherwise might be. So you can't count farm subsidies as "consumers of federal funds".
(It's definitely an artificial distortion of the market, but that's a different argument.)
I'm not sure how the conclusion follows from the premises. Farm subsidies do consume federal funds. Where do you think the funding for the massive pork-barrel farm bills comes from? Moreover, those dollars aren't necessarily passed on to consumers. In theory, the market for farm products is a perfectly competitive market and any subsidy to the market would result in cheaper prices for everyone. In practice, well, Cargill exists. Large agribusinesses are quite capable of taking subsidy rents and stashing them away as profit rather than using them to compete on prices if their market is more like a cartel and less like a perfectly competitive free market.
What does this have to do with a subsidy? You can do this identically without a subsidy (assuming you can do it at all). The subsidy just lowers the starting price.
It's no coincidence that the most rural, most Republican states are massive consumers of federal funds (via farm subsidies and transportation subsidies, mainly) and the most urban, most Democratic states are net producers of federal funds.