It is alarming. But the article is confusing. If the author’s representation of the law is correct, both of these girls can ride without a booster seat.
I looked up the law to see what it really says. It’s at http://www.leg.wa.gov/pub/billinfo/2005-06/Htm/Bills/Session%20Law%202005/1475-S.SL.htm
The relevant text is “A child must be restrained in a child restraint system, if the passenger seating position equipped with a safety belt system allows sufficient space for installation, until the child is eight years old, unless the child is four feet nine inches or taller.”
So both of these girls are exempt from the booster seat requirement. The author presented the girls as complying with a requirement, but stopped just short of saying so explicitly. I suspect this is another example of a sympathetic press working to extend the influence of an invasive nanny state.
(b) A child who is ((six)) eight years of age or older ((or weighs more than sixty pounds, the child)) or four feet nine inches or taller shall be properly restrained with the motor vehicle's safety belt properly adjusted and fastened around the child's body or an appropriately fitting ((booster seat; and)) child restraint system.
Their GOTCHA is the "properly adjusted" part. The girls are "under 16", and "8 or older"; but are "under 4'-9", so their regular seat belts can't be "properly adjusted" to fit them: it rides too close to their necks, rather than across the center of the collar bone.