What is tantalizing in nature is its capacity to adapt, and create elegant solutions to difficult problems. When a group of individuals are subjected to natural selection, they might die, unnable to adapt, but the remaining individuals still reproduce, until some critical trait emerges as a "tool" to adapt to the enviroment existence requiriments. This new trait can be a genetics mutation, that causes phenotypical changes that are crucial for adapting to new environments.
Take for example, a small portion of your house floor, and the products you use to clean it. If you kill 99% of the bacteria inside it then the 1% still reproduce, and that 1% is the fittest population to product A. Then, to kill that new population you'll need product A upgraded (more deadly) to kill the new population, until there is no more chemicals available to make such product "upgrades", and you end up with a superbacteria inside you home, which is not desirable. What a good soap will do the job, mealting bacteria's cellular wall appart, you'll spent many a penny to give you just, maybe, a worse cleaning result.
That's why cleaning products are not too efficient as they say they are, because your health is what counts. Only hospitals and clinics have access to powerful "bacteria killers", that are quite dangerous to human life.