"The government control the chemicals which farmers are allowed to use" - isn't really true - we have some of the laxest controls in the developed world,
(witness the imminent release of Spirotetramat onto the UK market this May), and if you add to that the fact that DEFRA are a wholly-owned subsidiary of "Big Agrochem", you have an environment which is controlled by big companies for profit, not the government for safety (as it should be..........)
Of course, not every farmer is irresponsible, but the overall "climate" in the business is to encourage chemical use - I farmed over 20 years ago, and was horrified by the quantity of them that was deemed normal, there was bags of free advice given by the "powers that be", including what was in those days the min of ag and fish and the NFU, ALL of it chemically orientated - if you wanted to do without you were regarded as a dangerous nutter, and treated as such.
I'm gratified that you've come across responsible farmers, I've stood and watched in amazement as a local farm contractor regularly ignored all the safety advice and tank-mixed his chemicals with no protective gear and a roll-up in his hand...... and then seen one of his "operatives" spraying in a 20 knot wind whilst doing Jensen Button impressions (all the spray drifted off into the surrounding fields and hedges.........)
I would contend that even the most conscientious farmers, even if they stick to the letter of the rules are contributing to the slow death of fertility in our soils, and the poisoning of our environment.
High-input farming's days thankfully are numbered, as the recent fuel crisis demonstrated, as soon as there's a relatively small "blip" in input costs, it's no longer financially viable - if we are to survive as a species, we have to develop totally sustainable farming, and soon - fossil fuels are running out, as are many other chemical "inputs".......