I think there are two main reason the fully "self-driving" end-to-end agents that demo well don't work.
1. Planning is hard and exponential decay: Most demos try to start with a single sentence e.g. "order me a Dominos pizza" and go do the whole thing. Turns out planning has been one of the things that LLMs are not that good at. Also, even for a low probability p of failure at a given step, you'd get all steps rights with probability (1-p)^n which gets bad as n grows.
2. Reliability matters and vision is not quite there yet: GPT4V is great, and there have been a handful of domain-specific open source models more focused on understanding screenshots but most of them are not good enough yet to work reliably. And for most applications, reliability is key if you are going to trust the agent to do things on your behalf.
Disclaimer: I'm one of the founders of Autotab (https://www.autotab.com/), we're building a desktop app that lets anyone teach an AI to do a task just by showing it once. We've gone all in on reliability, building our own browser on top of Chromium to give us the bare metal control needed to deliver 98%+ reliability without any site-specific fine tuning.
The other opinionated thing we've done is to focus on "Show, don't tell". We've found that for most important automations it is easier to show the agent the workflow than it would be to write a paragraph describing the steps. If you were to train a human, would you explain where to click or just share your screen & explain with a voice over?
Some stories from our users: One works in IT and sometimes spends hours on- and off-boarding employees (60,000 people company), they need to do 20 different steps across 8 different software applications. Another example is a recruiting company that has many employees looking for candidates and sending messages on LinkedIn all day. In general we mostly see automations that take action or sync data across different software applications.