Try factoring your time into the equation, Gilbert. I freely admit that I enjoy building kits. So for whatever an MJT coach costs (I'll take your getting on for £70 as a ballpark) I get upwards of 20 hours of building time, if you do a proper interior and weather it, without adding in the time spent researching and at the end of that I have an asset, the satisfaction of creating it and all the pleasure of running it on a layout to come. How much does 20 hours of golf cost?
If I pay £48 or whatever the going rate is for a Hornby RTR, all I need to do is take it out of the box, maybe weather and add passengers (a couple of hours?). Then I'm at the running it on a layout stage. There's far less creative process involved and (personally) I get far less satisfaction from it. And at the end of the day it's highly unlikely your formation is accurate unless you go down the kit build/buying route.
'Better' is subjective. I'd love a Larry Goddard or Dave Studley paint job on the coaches I'm building at the moment, but I'll do it myself because I can achieve a standard which satisfies me and at the end of the day it's mine.
I never thought I'd see the day when a Hornby coach cost more than a D & S kit, but now it's here I know which I think reflects better value. I appreciate that if you're not so confident soldering or painting and if you have the highest standards to match in what's already on the layout, it can be a bit daunting. This goes for anyone who's hesitant about building kits. Pretty much everything, they say, is 1% inspiration, 99% perspiration. If you're prepared to perspire, most people can get close to 99% of the best. It's that 1% which keeps Larry (and Ian, and Dave) at the top of their profession.