Why in certain cases goods are invoiced Higher than the Cost price in consignment Accounting by the Consignor?

I think this is the result of customs evasion 

  Sometimes some of the traders  make a statement with the shipment cost less to get a reduction in customs duties

I think it's kind of customs evasion in other words,to reduce the cost of custom

I think the consignor includes his normal profit in the invoice.The consignee is not supposed to pay any profit to the consignor but just sell the product at a price difference.

In my opinion it can not be a case of custom evasion. Since one evading customs will under-invoice i.e. will show less value to avoide duties. If he invoices higher prices, more duties will be levied. Second, customs is not payable if consignor and consignee both are in the same country.