You shouldn’t have trouble getting a taxi or rideshare, unless your flight arrives at an odd hour or there’s sudden high demand. If you’re worried, you could reserve a car service. Uber/Lyft is abundant up there even without the airport.

But yes, in contrast to SEA, public transport at PAE is basically non-existent. SEA is a much larger airport. It has light rail to downtown and more for a few bucks, will 100% have taxis and rideshare at all hours, and has 24/7 shuttle service to all major car rental companies. PAE doesn’t.

If you’re a tourist visiting Seattle, I would recommend SEA. PAE is more for locals who live north of the city for whom SEA is a far drive. Or for people specifically visiting points north of Seattle.