Biden is planning to impose a minimum corporate tax rate of 15%. I don't know how practical is this idea. It may still be possible to apply these laws on ecommerce and other businesses that operate physically. But online gambling doesn't exist in the physical form, and it will be very difficult for various governments to get information on their citizens who use these online sites to gamble. The government can come up with more and more innovative measures, but none of them is going to be 100% effective in preventing tax evasion.
No measure has ever the ultimate effect to a cause it is meant to address. Sure, you could say 0% corporate tax, but what's the point of doing that...
You can put the death penalty on stealing anything worth more than $2, and yet you will see people stealing something for $5. The problem is that not all scams are ill-intentioned. Imagine you are the boss of three thousand people, you know many of their faces and know that many of them have families. Your business is not going well this year and you really believe it will go well in two years again. If you file a correct tax report, you are insolvent. So there are also these cases where people emotionally justify their illegal actions.
As for Biden, that's true and he seems to have a plan on his own obviously. But isn't Delaware anyway the hotspot for so many companies? As far as I know they are already offering tax rates way below 15% anyway.