Why is taxing imports more effective than raising import tarifs?

Taxing imports sometimes throws up notions of the boxes shown in association with this question - however the loss in Global taxation directly related to the import and export of goods and services in recent years have been more tied into tax avoidance by corporates such as Google and Apple who's income comes more from online applications, advertising, streaming, downloads etc.

Clearly there is a greater pool of those taxes to go after than physical goods based tarrifs. Also taxing imports is a fairer and more direct way of raising taxation incomes as it usually comes from business profits. That is of course if those local taxes are fairly calculated which has not always seemed to have been so in the past which matters such as intercompany charges seemingly abused to avoid the payment of local corporation tax