I never had any problem with UPS; it's FedEx that seems to screw us over again and again.
To be honest, I think they're all as equally hare-brained as each other. A lobby seems to to confuse the hell out of them, or at least, their delivery policies are such that they don't seem able to consistently buzz the correct bell...
As for international delivery charges, both US and UK customs have majorly cracked down on items slipping through the cracks. You would actually have to have it marked as a gift to avoid charges now, whereas a few years ago it was luck of the draw.
It's also more costly for the recipient if you use a courier rather than regular carriers like Royal Mail or USPS, because the couriers pay some fees in advance, and then charge you for them, plus a handling charge. If possible I always prefer to receive and send things via the normal carriers, but with tracking, signature and insurance to increase reliability up to an acceptable standard.