I think the answer depends a lot on the use case of each business's website and what the business owner/employees expect from it.

Is the website a storefront? You'll be spending a lot of time maintaining integration with payment networks and ensuring that the transaction process is secure and can't be exploited to create fake invoices or spammed with fake orders. Also probably maintaining a database of customer orders with names, emails, physical addresses, credit card info, and payment and order fulfillment records... so now you have to worry about handling and storing PII, maybe PCI DSS compliance, and you'll end up performing some accounting tasks as well due to controlling the payment processing.

Does the business have a private email server? You'll be spending a lot of time maintaining spam filters and block lists and ensuring that their email server has a good reputation with the major email service providers.

Do the employees need user logins so that they can add or edit content on the website or perform other business tasks? Now you're not just a web host, you're also a sysadmin for a small enterprise which means you'll be handling common end-user support tasks like password resets. Have fun with that.

Do they regularly upload new content? (e.g. product photos and descriptions, customer testimonies, demo videos) Now you're a database admin too.

Does the website allow the business's customers to upload information? (comments/reviews/pictures/etc, e.g. is it Web 2.0 in some way) god help you.