"Tax avoidance" is not that simple. Tax laws are complex. Often businesses and governments have different opinions on what should be paid, so all tax bills can be opposed and challenged.

I own a small one-person software consulting company in Switzerland, working with international clientele and paying myself a salary. I _still_ have discussions with authorities on what should be paid and why, because its in their interest to claim the most, and in my interest to pay the least (and there are no less than 20 different incredibly complicated laws regulating my business). Often I prove that I am right, and tax claims are reduced, sometimes substantially. If I have paid automatically everything that is claimed by authorities, my business wouldn't survive a single year. For larger companies dealing internationally, it is way more complicated. 50 years ago, to own a "transnational corporation", you had to be a billionaire and run a quite complicated business machinery, and laws were written according to that. Now, a one-man software company can be transnational, but some laws were not updated to reflect it.

Thus, allowing the government to peek into and seize my bank accounts at its caprice would be the disaster for me and my business.