Radials are easier & fool proof to test.
Except they are not.
Yes, it turns out GN3 does not specify the N to be tested (just L&E for Zs and polarity) but that does not make them faster to test
to the same standard.
With a ring figure-of-8 test you get a very good indication of a bad joint as even 0.05 ohm extra will stand out. Yes, it could be a spur (see earlier) but it is easier to be sure than having to compute the cable length & resulting expected resistance for a radial.
How many rings have been in complete on an Eicr,
How many radials with CPC open that did not show up as a fault to the customer?
Yes, an open L or N on radial is immediately obvious, but an open E is not and far more dangerous as several outlets could be impacted, where as the ring would probably only have one socket open E (if at all).
Also the open ring is less of an overheating risk than immediately though - yes one leg is down to 2.5mm on a 32A MCB but the other live conductor that is still part of the ring will have its current shared, so you don't have as much total heat from the T&E combination as you might initial imagine from the loads on that leg, and you would expect faults to be anywhere so many open rings would be about half way anyway.
Also it might stop the overloading of circuits especially high loads on the same ring,just because it’s a ring.
Why?
Do you expect many householders to think "Oh yes I have a ring circuit so I can put on at least 8kW of load these 4 13A sockets, but those are on a radial so I must keep it down a bit"?
Of course they don't do that!
If you have that sort of an overload it is down to bad design, and if the person installing stuff is not able to do the design and deal with the usual suspects for overload such as ovens, etc, that are already supposed to go on radials, why are they doing electrician work?