Friend broke the law, got caught, and authorities demanded the fine (or jail time). Sorry, I don't see anything wrong with that. Sure, they could have been lenient for a first time offense, but they certainly don't have to, and given the amount over the limit, can see why they wouldn't. Since there are limits on alcohol and cigarettes pretty much everywhere, it shouldn't really be rocket science to check on this kind of limit before entering. That it was basically a transit layover doesn't change anything.

Monthly salaries, by the way, are hardly relevant when customs authorities are doling out fines. They are doling out the fine based on their protocol. It's not their responsibility to determine what one can pay - the easy way to avoid having to pay an unaffordable (or even affordable) fine is to not break the law. Simple as that.

If you, OP, are from California, try this: bring an orange back to California with you next time, and don't bother declaring it. See how customs there reacts when they find it. Especially as you mention you have trusted traveler status. In fact, if you want a preview, look at the trusted traveler thread where a GE member got fined $500 for bringing a single banana back without declaring it, and had their GE revoked and a mark on their record, and likely ineligible to be re-approved for GE again, or at least, for many, many years. Is that wrong, according to you? Your OP seems to even indicate that you understand the law was broken, but that since it was an oversight, there shouldn't be the same punishment. But that just makes it sound like a DYKWIA statement. So your friend should take responsibility for their actions, however unintentional, pay the fine, and move on.