Bromptons are expensive hence why I don't have one but they are fully certified and tested for a long life with decent components. These don't look strong or built to last, the basic crimped dropouts on the forks and other parts look pretty poor. It's no bargain to pay half as much for a bike that lasts only a couple of years and puts your safety at risk.

I thought the whole point of that frame design was the need for steel or possibly titanium so the flexing of that downtube doesn't cause premature fatigue. To just keep the same frame design but move to aluminium unless overly compensated for with a much thicker possibly non-butted tube seems less than ideal. As you change materials the frame design should change quite a lot. While I was at a recycling centre sometime ago I saw a basic generic folding bike where the chainstays had sheared off and twisted and a huge number of deep scratches to the underside of the frame downtube. I didn't know how old it was but it looked like a pretty horrific failure possibly injury causing. The bike was folded but I think that was purely to make it easy to dispose of as the hinge itself looked fine. It was clearly aluminium too due to lack of corrosion on the frame itself even though other parts were corroded. It wasn't a brand I recognised and the wheels weren't attached and some other components had been removed. What was obvious about it was the complete lack of strengthening in its design and it looked exactly like the sort of frame that would fail. I don't know the date of the bike as that was made difficult by the lack of components but if I was guessing somewhere between 2006-2012. The stem was still attached and was a basic quill stem, non-folding.

Bicycle certification has improved over the years and frame tests have become much better and stricter. There is better indication now of weight limits and more requirements for manuals to give detailed information regarding of normal use and expected lifespan. Even in China many Chinese avoid Chinese branded goods due to safety concerns and prefer western brands even if the products themselves are manufactured in China because they believe they will meet proper safety standards and won't have dangerous cost-cutting. Even in Taiwan which is the source of probably the best bike components in the world nowadays there is a large low end sector where they assemble mainland Chinese parts to put a 'made in Taiwan' sticker on them or small factories that produce low end product that sells on Taiwan's great quality reputation despite being poor quality. The risk is pretty much eliminated by buying properly certified products that have been legally imported commercially into Europe or US and not a personal import.