Yes there are some jobs where the skills and knowledge of a tradesman are required. But there are also a lot of mainly smaller jobs that are supposed to be done by a tradesperson but which actually require very little skill or knowledge. That's why hardware stores sell all types of electrical and plumbing fittings to anyone. Lots of us do our own minor repairs and modifications. I just bought 5 litres of restricted insecticide to poison ants, underground termites etc in and around my house. Regulation says you have to be a licensed pest exterminator to use it but full instructions on methods and safety are included and you don't need to be particularly clever to understand them and do a proper professional job yourself. So in one day for $100 I will do what a licensed exterminator would charge $2,000 to do for exactly the same result.
