How to do TDD in web development

I understand the basic-basics of tdd and it makes sense, but for web development it could be more time consuming to automate test then to write the program and run through a manual checklist. What I mean is that if I have a php or node.js code that creates a web form, it would require maybe much more time to write a check whether the form is shown correctly and etc.. correct me if I am wrong, but how do you apply TDD in web development? For example how would you write a website or wordpress plugin and automatically test it, if all it does is showing a gui and saves the information into a database, wouldnt it be really much more time consuming to check the database, create a test database state and etc?