Do you have to pay tax for everything in Washington State?

Not quite everything.

There is no sales tax on groceries (with a few exceptions such as soda and liquor).

There is no sales tax on rent (there is tax on hotels, motels, vacation rentals).

There is no sales tax on professional services (dental fees, attorney fees, etc.).

There is no sales tax on insurance premiums.

Yes, there is tax on most retail goods and services...everything from eating in a restaurant to shopping at Target to getting your oil changed.    It really, really adds up especially when you buy something large like a car. 

Because a sales tax is superior to an income tax. Unless you own a business there's no meaningless forms to fill out, no trusting the honor system of reporting, and everyone is guaranteed to pay a share even if income was obtained illegally, yet poor people will pay a lesser share due to their higher share of income being spent on tax-exempt food. It is one of the few things my state does right.

Washington State uses sales tax as the main source of taxation.  There is no state income tax and property taxes are reasonable.  Sales tax can be upwards of 11% depending on which county you make your purchase in, King county (Seattle) being the highest.

That's true of most places. Different states put a sales tax on different items.

No.

For example: groceries and prescription drugs are exempt from state sales tax.

Note that there ARE states that charge sales tax on groceries. (I live in AR which did so until last year's law change).

I've lived in states that don't charge sales tax on periodicals (and others that do).

I've lived in states that don't charge sales tax on "eat in" restaurant food but DO charge on take out (and states that charge on both).

I've lived in states that don't charge sales tax on clothing..and states that do.

etc.

That is what  a sales tax does.