Hi, @MData !
Thanks for reaching out, I’m happy to provide some context.
The two pieces of information you shared are about different things. The first point is referring to how Shopify automatically calculates taxes on your orders once you’ve configured your tax settings. The help document that is from is about how to configure your tax settings within Shopify. The second point is referring to the fact that if you’re located in BC and sell goods or services, you’ll need to register for PST with the government (not Shopify). The help document that that’s from is a general tax guide to help you understand sales taxes in Canada (and not specifically about how tax settings on Shopify).
Once you set up your taxes by following the steps outlined here, taxes will be charged automatically. You can create tax overrides if you have products where the default rate doesn’t apply.
I hope that makes things more clear! Let me know if you have any other questions.