You may not WANT to overuse it but it happens pretty much everywhere for exactly the reason you stated - it isn't free.
This means that people like DEFRA (formerly MAFF) are under tremendous pressure to continually increase the "recommended" levels of fertilizer (and pesticide, herbicide, fungicide) used per acre so that the "rural economy" - ie, the fertilizer salesmen - do well. In the western world, fertilizers are also a capital 100% tax deductible business expense so they're not exactly free but come at a penalty of short-term cashflow only.
When the subsidies are pegged to be available to the very biggest farmers (as in the UK, small farmers are expected to do the capitalist thing and die because they're not subsidized efficiently by the state.... don't worry, that confuses me too but is true regardless) and those subsidies are in part discretionary based on the "efficiency" of your agriculture which is partly measured by how well you fall in line with DEFRA's recommendations... well, when that happens Monsanto sell a lot of fertilizer.
You should also note that "efficiency" has - in DEFRA terms - a one-to-one mapping with "monoculture" which by definition relies on fertilizers as otherwise the soil is leeched of N and P and cannot sustain crops (the old method was to leave land fallow for two years, preferably growing clover as a Nitrogen fixer but this is not "efficient"). It also becomes vulnerable to pests, fungi and weeds that are unable to gain a foothold in a crop-rotation system.
So yeah, it's farmers. But they are not alone in this farce.