Things used to be a lot more controlled in the US until the mega home stores opened. You could always get NM cable, boxes and devices at the hardware store but you were not going to find panels and meter sockets. You also paid full retail in these hardware stores. Now the home store has everything and is also competing on price trying to get trades in there but that makes these jobs look overpriced to the customer who thinks "Hey I can buy a panel full of breakers for $150. How hard can it be to install".
The only real control is the PoCo that wants to see a permit before they will reseal the meter but that can backfire too. You can end up with a homeowner handling live service conductors, a truly frightening thing.
