There is a need of stable (not frequently changing) e-commerce app that can be hosted and supports stripe/PayPal and "shipment tracking".
WooCommerce requires yearly payment for shipment tracking.
When discourse is available for free, there is no reason why WooCommerce alternative which can provide more out of box support can't be free.
Today what options people have? WooCommerce, Shopify (SaaS) and legacy apps like Magento, Presto, Opencart.
This is not enough - most e-commerce development happens on agencies selling their services. We can certainly provide more out of box features with help of open develop model.
I just did a quick search and found that there is a plugin called advanced shipment tracking for woocommece which seems to be free and gets the job done(i am sure it has a paid version too but the free one seems to be good enough, judging from the reviews)
Also e-commerce site owners are entrepreneurs and the primary goal of any e-commerce site is to make money. The primary goal of a discourse forum isnt making money. E-commerce owners are more likely to invest in tools that help them grow their business, unlike someone who runs a forum, where there might not be such a motivation.