I doubt that's a 5mm thick layer of ptfe- scrape it back a bit. It looks like the tape just goes over the fitting where it enlarges, making it look like it's all tape.
P.S. leaning to DIY domestic plumbing is very easy & rewarding. You only need a small selection of tools to do pretty much anything.
Aye about £50 worth of tools (if you're buying from screwfix vs the really cheap stuff) gets you 90% of the commonly used ones, as IIRC you can do most plumbing with a pair of "water pump pliers" a mid size adjustable, a couple of spanners, and something to cut the piping with (either a hacksaw or dedicated pipe cutter).
It does tend to add up over time as you buy more specialist stuff for odd jobs (tap wrench, blow torch & heat mat), or tools that make it easier (long reach sockets etc), but for a lot of it if you've got a tool kit already for your car it's only a handful of specific tools needed.
One tip is to get some gardening "kneeling" mats, one of those "yoga" mats that you use camping or similar (the foam mats they sell for kids play rooms are great, and cheap) and cut it to size so when you're lying on your back under the sink, or crammed into a small spot trying to do something you're a little more comfortable
Nothing wrong with that. It’s a radiator replacement.
If the threads were different (metric/imperial) then he’d would have had a fun time trying to join it up - even more so to make it leak tight. If he somehow managed to do so and packed it out with PTFE then you’d know by being able to physically rock the fitting and see the movement (PTFE is not that strong)
PTFE is required because as you know... material expand when heated and contract when cold. A radiator is in both of those states.
On the flip side if he had charged more because of the amount of possible work involved to to make that pipe work 5degrees straighter would you also be complaining that it was now expensive?
Also if the tails are a different material to the radiator it'll expand and contract at a slightly different rate.
Radiator tails are my least favourite thing to do from a leak POV, whilst replacing taps is the worst from the "how the **** do I reach that?" pov - after trying to change the kitchen tap a while back I ended up getting a bunch of "ratchet" spanners (with a head that was hinged) and long reach sockets as I was trying to undo a nut that could only be turned about ~1/8th at a go in a space that was extremely cramped. The long socket let me do it up/undo it about 90% of the way, then swap to the spanner which as I didn't have to keep reseating it blind was quite fast.
