I've been wondering about the same thing. In the last 2 months there have been a lot of successful reports of N from D. I'm guessing either D has a way around the custom or the custom just don't really care that much about suicidal people importing lethal drugs in relatively small quantities.
The amount of drugs passing over borders via mail is high. Especially in small quantities and now during the pandemic and subsequent lockdowns. It's a lot of work to catch everything. The sorting offices and customs are only able to check so much with absolute presicion as there are only so many hours in the day. So there is a definite element of 'luck of the draw'. They look for the obvious stuff first and can pick up a dodgy package with one and and pass onother with the other hand. The legal repercussions of an intercepted package will depend largely on where you live and the local laws but if you are a first time offender buying s small quantity for personal use I imgine it will be unlikely you will receive much if any punishment. That said, it will be logged at the least and people report receiving a 'love letter' from their local authority 'slapping them on the wrists'. So yes, there is certainly an element of risk but it is all relative to your criminal history, the amount you import, the local laws and a bit of luck. The most we can do if we insist on taking a risk to go ahead and import N is to make it as calculated a risk as possible and take precautions where ever possible. It probably takes a bit of creativity to do all that can be done but there i not 100% safe/certain way to do it. This is the risk we have to decide whether to take or not.
Whatever the case, the advise from any decent lawyer or solicitor is always say nothing. If asked you say I don't know and nothing more. Whether due to questioning for an intercepted package or a follow up visit for a received package. If you receive your package the advice is to store it away from your home where possible. There are threads about it here I think. Also some info on it in the peaceful pill handbook.
It's a serious thing to consider though, no matter how well you can handle the police etc it's not something anybody should do lightly.
It's an unfortunate necessity for some but really should be avoided if possible. I assume that goes without saying though.
In answer to your question I think most people taking the risk to import N do fear the repercussions but are desperate. It's all relative, right?
I expect the sellers do too. Maybe that is actually what you're refering to? In their case I don't know what to say.