I cannot see the sense in buying a new sax from a seller, or store, that I can'nt have 99% confidence it will play perfectly straight out of the box.
I get it that it may need an adjustment around the 3 month mark, but cannot see the point in wasting time on a boomerang. What do you play when it's been sent back and waiting for the next package to arrive?
We all make our own choices in how we buy, and what we do when we get new instruments. I've bought from online suppliers, although when I was choosing a high end tenor, I chose to visit a shop and select an instrument in person. It was an enjoyable part of the process. However, discount online suppliers open up options for those at a different point in the market.
It's a matter of economics. This is a part of what makes it cheap. And they really are cheap, in real terms, compared to when I started playing. My first sax, bought for me by my incredibly generous parents (who couldn't really afford it at the time) was a not-very-good 1970s Buescher. It cost £290, second hand, without a mouthpiece, in 1980. At today's money, that would be £1,467. A basic G4M tenor is £350 new, today, and doing the calculation backwards, that's about £70 at 1980s prices.
It's also not that all of them get returned, just maybe a higher proportion than in dealers which invest in technical staff to check horns are in perfect shape prior to despatch. Even those that do, unless you buy locally and collect in person, you can't be anything like 99% sure they'll play out of the box, as however well set up it is when it leaves the shop, as getting thrown about in the back of a delivery can van can put any sax out of whack.
All of this is really only relevant in the case of G4M for buyers in the UK, and maybe near-continental Europe, where the turnaround time is quick. G4M are based on the outskirts of York, a small city in the middle of the UK with good transport connections. It would only take a few days to return a sax and get a new one sent out. In my case, during that short wait, I'd just play one of my other saxes......
The supply bit is only one part of the whole supply chain, of course. There is large scale low cost manufacture in China, incredibly cheap containerised shipping around the world (it costs more to ship an item from a UK port to its distribution centre than it does to ship it from China to the UK border), e-marketing instead of hugely expensive city centre shops and so on. However, reducing the cost of expensive, highly skilled staff in the UK is a pretty big part of it all.
I am not saying the G4M business model is my favourite economic method. However, it does work, and it's the box-shifters which have democratised musical instrument supply to the extent that pretty much anyone who wants to try playing an instrument can give it a go.