Why do some companies offer extra cheap shipping, are there any hidden fees?

If it is a full container, there is no hidden fee.

If it is LCL, the shipping company can choose not charge or charge less at the port of departure,and most part or all of the charges will be collected at the port of destination. In order to avoid the hidden charges, we suggest our customers to do the FOB terms or CIP terms. Most of the customers will face the uncertainty of the charges of the port of destination if they do the CIF terms, and in the CIP terms, the charges of the port of destination will be borne by the seller, and the buyer will only bear the taxes.