I don't mind doing small web jobs. There are absolutely folks whose needs are small but important, and I'm happy to help small content creators make their Ghost sites awesome. They're sort of like a snack-size bag of popcorn - they're quick and satisfying, and I can totally finish one off between when my kiddo goes to bed and when I do.
(I also quote plenty of jobs at well over $100, so don't get too excited.)
$100 jobs are well-defined. They are generally a single bit of work, clearly scoped. Examples: Add a views counter to posts pages (for analytics the client had already set up). Add dropdown menus (to a theme that was otherwise 'perfect'). Add a tag cloud (with a clear design brief or mock-up). Add a related posts column (for a theme without one). Add a 'hero' section, or a background image. Switch to using WEBP images, or move a script out of code injection and into the theme so it'll stop blocking the page render. Those sorts of small single jobs can be $100 each.
$100 jobs are asynchronous. They don't need a Zoom call to define the scope or explain what's needed. They can (and often should) include screenshots showing the problem, but don't require me to watch a ten minute video in which you explain what you want. The 'squishier' your requirements are, the less likely I'll quote your job at $100.
$100 jobs give me what I need to do the work without lots of back and forth. If I'm customizing the theme, I need a zip file downloaded from the themes page of your site, or admin (not lower) access to your site so I can get it. If I'm changing your header image, I need that provided, at high enough resolution. If I have to go back to my client a bunch of times for more information, it's no longer a $100 job.
$100 jobs don't require a detailed contract, because they're a single bullet point of work, perhaps with a couple reference images. (A screenshot of the current page with what needs to change clearly indicated is great, too!)
$100 jobs don't need a fancy invoice or payment terms. I send you a Stripe invoice and you pay. If your process of paying me requires work on my end beyond sending an invoice, then it's not a $100 job.
And despite the focus on $100 jobs, it's good advice at any level. Spending my developer time chasing you down for something you should have given me before I started is time that I'm not writing your code, which means your job takes longer, which means it costs more. :)