UI Examples for Backend / Admin / Data / Crud WebApps

I see tailwind. I see a lot of resources to build the cleanest landing page with tons of thought put into it.

But I cannot find any examples of handling the more businessy UI UX application design. The stuff we built at work all day.

For example an app that manages taxis.
You have a list of Taxis, a lot of details.
A taxi has a list of drivers, you can edit add delete them.
A driver has a couple of licenses, you can edit add delete them.
A taxi has a list of contracts, the contracts can be edited, a contract is always assigned to a supplier. You also have a list of attachments.

There seems to be no guidance on this. As soon as actual functionality is needed, things get weird.
Even simple apps like todoist or strawpoll. You open them and you're like... ehh. It works, but suddenly all the high and mighty designs that land in a HOW TO DESIGN A FORM guides are out the window, because you actually have to do stuff.

Should it always be master detail? Should I edit the details on a popup or on a new page?

Do you have any examples of websites like this? Any design guides?