You would think so but no, in fact, such apps have been getting more numerous yet harder to make over time rather than what you'd expect.

Causes:

1. Web platform is very unproductive and hard to learn compared to what was available in the 90s. There's no widely accepted, robust and modern equivalent for Access, VB, etc. These tools were designed to be easy to learn. Smart business analysts could throw something together. It'd be a mess but you could graduate it into a "real" app, or something approximating that, without needing a rewrite. This culture is gone. No, the web is definitely not as easy. Think about how complicated just binding a DB table to a paging table view is. HTML doesn't do this, SQL queries can't even be serialized natively, so you end up needing a custom web server, a backend framework, a frontend framework, extra JS libs or widgets to give paging or scroll or fast updating search. Consider that with Access or FoxPro it could be almost all GUI driven.

2. Although a few complex requirements got simplified out by the march of tech (e.g. offline access, supporting downlevel browsers), mostly, enterprise requirements became more complex. Some of this is reasonable and legitimate, like integrating with SSO systems, mobile versions, better auditing, more beautiful UIs and elimination of scheduled maintenance periods. Some of it is of questionable legitimacy. A lot of CRUD apps become over-engineered because of CV-driven development. Does your internal app for the business really need to run on AWS Lambda for scaling reasons? No. It doesn't, because the traffic levels are predictable a long way into the future and a single dedicated machine can do what you need. Will you be able to find a developer who will actually admit that and throw together a simple Spring Boot or PHP app, instead of trying to Web Scale™ it up the wazoo? Maaaaybe.

3. Platform churn. Businesses don't like rewriting apps but from time to time they have to, because either they can't find anyone who knows the old tech anymore e.g. COBOL, or the platform goes out of support. So the same stuff gets rewritten again and again without underlying change in business requirements. Worse, these projects often fail and may need to be attempted multiple times.

4. Many of these "standard" apps are astoundingly complicated. "Regular UI" can involve complex and frequently changing UI designed to navigate large datasets. Is Facebook a "regular UI with a login form"? Well yeah but it's still a lot of work to build. Think about the complexity of Bloomberg terminals for example.

5. The idea that all business apps were written by 2000 already is false. Even today there are a shocking number of business processes that have little or no IT automation; they're still based on physical paper. I didn't believe it myself until I worked in the enterprise space for a while and saw it with my own eyes - there is still enormous business value that can be delivered from writing new "standard" apps. And of course, even once you get beyond paper the long tail of business processes that are automated using an unholy and unstable mix of nightmarish Excel macros, PDFs and executive assistants is more or less unlimited.

I think programmer salaries are partly being squeezed upwards by the fact that we've made the tech stack so difficult to learn. Have you ever watched someone try to learn programming from scratch, like at a bootcamp? I have. It's excruciating. I watched as they tried to teach someone who'd never coded before how to write a "standard" CRUD web app, using Ruby on Rails. Total failure. They were not even remotely in reach of the goal. To succeed with even a basic app they needed to learn about Ruby, SQL, HTML, HTTP, ORMs, JavaScript, JSON, CSS, and of course the UNIX fucking shell because even if you pay $$$$ to Heroku to simplify deployment, it's all driven by a CLI anyway!

Back in the 90s one reason Microsoft won was that they managed to hide the complexity of their underlying platform with beginner friendly languages and tools. When Windows programming starting sliding into irrelevance and they dropped VB to try and compete with Java, we made the on-ramp way steeper.