Nah. Shippers, DHL, UPS, FedEx. USPS, et al are on the hook for collection. The privates just do it online. You actually have to go to the post office and pay, they will probably get to online someday.
Now, what you get charged is anyone's guess. DHL was trying to squeeze 42% from me. I thought tariffs from England were 15%. Who knows.
handling and brokerage fees probably.
good luck finding a schedule.
items being sent through the postal services may or may not be treated uniformly.