It is not a scam. Scam means a fraudulent way of getting money.

It is called IMPORT DUTY, IMPORT TAX. google it, learn something, maybe. Like had you never heard of import tax? That it is set by government of each country? Your ignorance, your problem.

If any PO [international depot, Customs] of any particular country does not check every parcel, or every parcel above a certain stated value, you are fortunate. Try Canada or any typical EU country; some of them check everything.

And, 20% import tax and 7% VAT is not equal to 27%.

The import tax is calculated on the stated value or invoice value of the goods, converted to the local currency at the exchange rate that day. That amount is added to the value of goods.

Then VAT is calculated on that subtotal and added. In other words, on the converted invoice value of the goods plus the import tax.

The VAT is also charged on shipping costs.

Slipping parcels by Australian Customs is also difficult.

Right, and airmail usps parcel from USA are almost never caught by customs also, as to Thailand.

It is really simple. I don't get it how people are so dumb. In Canada (so it is not only Thailand dummies) it also happens that if you order from USA and get it shipped by FedEx and UPS, you often get charged over the original amount. This is because these companies do broker the goods for you instead of you doing it yourself. You are paying for the "service".