Understood. The duty/tax thing varies by carrier. The short version is that anything that comes in through Royal Mail will rarely get caught if it's below 2.2kg, and generally 'looks' like a low value item (a value is always declared on the packaging, but as noted, the Chinese imports tend to be very low; we do show a reduced value, but we have to keep it within reason). Our 'lowest cost' shipping ultimately is delivered through Royal Mail. This will get interesting depending which way Brexit goes; if everything coming in from the EU also has to be 'checked', then Royal Mail are screwed, more so than they already ar with this stuff, and stuff will either get very slow, or slide through even easier.
The other carriers (DHL & UPS) are far more modern, and everything is transmitted electronically, and the declared value is supposed to include the shipping cost, which of course they know, so it's fairly easy for a package going through them to pick up duty, even if the declared value is low. Anything over $150 ships with one of those carriers, since we have to insure them, and that's either not possible, or stupidly complex with the lower cost options. We do have options though, we're working with both of them to waive the handling fee. This is a noegitated option, and I'm not sure if either will comply, but I'll know by next week. That's option 1. Option 2 is to deliver 'duty paid (DDP), this would of course mean that there's nothing required upon delivery, as it's either pre-paid, or charged back to our account for later payment. We're looking at options around this as well; there's various services that can figure out the duty (which vary by country, and product, so it's complicated), but the integration is difficult, and the shipping logic we use is already quite complex, so I'm cautious about messing around with it at this time of year. Finally there's another company owned by BA that might be a decent option, they do delivery DDP, and they're quite quick - in the 4-6 day range). We have a quote from them that we're going back and forth on.
This is a long way of saying that we get it, I've plenty of experience of ordering stuff from the US into the UK, and we're always looking to make the experience better. This feedback helps though.
