Because it's cheaper. Duh.
If a company charges too much people don't buy their products and go to a competitor. Likewise if a government charges too much tax businesses change their tax nexus to somewhere else.
It's unreasonable to expect a business to operate against its own self-interest. Any system that requires it is bound to fail.
Governments must design their tax systems to be competitive if they want revenue.
Arguing that companies should opt to pay more in taxes is like arguing that consumers should buy a product that costs more. It makes no sense. It's the reason why Walmart exists and why people don't buy local. It's a matter of practicality.
You can make all the moral arguments you want but the facts are that people and companies are going to act in their own self-interest. Until we can be frank and accept this as fact, we can't design moral, legal, and tax systems that work effectively.