Fit the tape to cover your back, some olives may be slighly out of square.Copper olives are much softer, but more expensive
Very surprised that you gas men are not obliged to do this
Any 'out of squareness' (you mean roundness) will correct itself as the olive is tightened onto the pipe. Don't even go there - the cost of a copper olive! You're having a laugh! How much more Turkish Lire does a copper olive cost compared to a brass one??
'Gas men' are obliged to make compression joints correctly according to the manufacturers instructions, which means they are obliged to NOT use PTFE, if you study the regulations.