Several of the basic chemicals are less safe for the operator to use - e.g. Caustic soda is very irritant, while Citric acid and Sodium hypochlorite are irritant. Formaldehyde has many safety issues. They also list phenols as ineffective, but the High Boiling point phenols are effective. They list Iodophores as ineffective, but again the Acidified Iodophores are effective. These facts are supported by MAFF approvals.
People use or recommend the basic chemicals because they are cheaper.
People ask how they can make footdips etc if they are travelling round. Foot dips can be made using a 2 gallon bucket and scrubbing brush. Wheel sprays can be made from garden knapsack sprayers. You can get these products from any good agricultural supplier or agricultural chemist. Click Here to find your nearest disinfectants stockist .