That and the fact that the line between custom software and customizations of pre-written software isn't very clear (or if clear, draconian). The way they wrote

That and the fact that the line between custom software and customizations of pre-written software isn't very clear (or if clear, draconian). The way they wrote it, a custom WordPress template sounds like a customization (therefore taxable), but a site not hosted in a CMS is custom (non-taxable).