Ship Sales Tax
Whenever a member of your nation sells a ship, the amount of ships owned tax that ship was worth is payed to the nation.
In example, if my nation has a tax of 500 gold per ship, If I sell a Trade Galleon, I have to pay 500 gold is automatically subtracted from how much I would have made and is sent to my nation's treasury.

Upkeep Bailout
If a member of your nation cannot pay their upkeep, money is subtracted from the treasury to pay enough of the upkeep for that member not to have to sell cannons or fire crew. The hard limit is 5% (Up to debate) of the nation's treasury.

Appropriations Bill
Allows that nation to decide how the money in their treasury is split to certain task. In example, for the upkeep bailout, a nation can decide that 50% of the money in their treasury will go to paying upkeep. As more laws are added that act like the upkeep bailout, appropriations of the treasury might become more useful.

I don't get the first law. I understand it but I just don't see its usefulness.

Second law is a great idea.

Third law would make it a lot easier for countries with smaller treasuries.

The first law is another way for countries to gain income which is very useful when your country makes only about 20,000gold a day.