The most important thing for any kitchen is the cleanliness of it. That goes for the people who work there, the owners and most especially the people who eat the food that is prepared, cooked and served from it.
For the people who work in it, there are many sharp surfaces which may cause an injury such as knives, mandolins and meat slicers and they need to know that when they have an accident, as they surely and regularly will, that they are unlikely to be infected with anything that is going to make them ill.
The customer of course has to have the confidence that, when visiting a restaurant for a delicious meal that they hope is going to be an olfactory delight, and they are not going to ingest something that is going to keep them up all night or necessitate a visit to their GP practise or worse.
Lastly, the owners need to have confidence because if the customer does have a bad experience, the consequences are likely to be dire. For a start, in monetary terms, the costs in compensation to poisoned patrons is likely to be extremely high.
Yes, there is public liability insurance to cover it, but the premiums after such an episode are unlikely to be friendly when it comes time to renew the policy. But worse for the owners, is the damage to reputation which may never recover and it only takes news of a single episode to emerge and that may be all it needs for the business to go down.
However, a busy service is a high pressure workplace, it isn’t always possible to be as thorough as everyone would like and things do get missed, and so getting professional cleaners in during the kitchen down time to make sure that everything is as spotless as it can be made to be is an extra insurance for everyone.
Every food preparation gets an annual hygiene assessment and displays a card showing their rating, but the bacteria don’t wait annually, they are always there and the battle to contain them is one which will never cease.