A road sign indicates a speed limit of 30 mph on a ... and they’re set in state statute by elected officials, so you could call that politics, but there’s more to it than that.
The WSDOT recommends those in need of alternative traction devices to visit the Washington State Patrol's Vehicle ... which are available on highway-advisory signs and highway-advisory radio.
As other states start to reassess their prioritization of expanding highway capacity in the face of ambitious climate goals and other transportation needs, Washington is still in denial mode.