One common theme is that companies used to treat good employees as assets. Now they treat all employees as liabilities.

What changed? A lot. The underlying theme across all companies, to both employees and customers, has been "see how much abuse they'll take before they leave", which sadly has had marvelous results because the answer is... a lot. Notice that at least half of the largest companies by market cap have no actual support at all.

Add in that tuition has exploded, it became cheaper and quicker just to import people than to train them.

>I wonder why companies don’t do this anymore. Is it something to do with the monopoly AT&T held, is it related to corporate tax structures, is it related to how easy it is to find PhD graduates who studied similar topics of interest, or is it something else entirely?

Companies do a lot less to retain employees - fewer pensions, fewer accrued benefits and perks - so it's much less attractive to train when you are assuming attrition instead.

The company I work pays normal salaries for their PhD students.

That pretty much standard in Germany in industrial research departments.

The answer to your question seems straight-forward: they still do.

1. Companies have tuition reimbursement for general employees, but it's usually nominal at $5k/year and part-time education is implied.

2. Executive MBAs and more selective executive seminars are covered by companies so the focus will be better. These aren't cheap (easily $125k/year) and might come with early exit penalties. I'd be surprised if the Bells lab offer didn't have similar clawbacks.

3. Tuition in 1970 isn't what it is now! Wayyyy cheaper!

I don't think companies pay for you to go do an MS or a PhD full-time on company dime. At that time AT&T was a monopoly and may have had money to burn on this. There also may not have been expectations of hyper-growth from the stock market that exist today.

AT&T still pays for various MS courses (mostly MSCS, MS data science and cybersecurity) you can do on a part-time basis. It's quite easy to get the tuition reimbursement for it.

This is very common in Europe. PhDs are sponsored by a given company

The Bell System was, in modern parlance, fully vertically integrated. They didn't own the mines that the copper for the conductors was extracted from. And they didn't cast the copper ingots. Though they were interested in the metallurgy. Because they drew their own wire. And cables. And transformers. And vacuum tubes. And so on. It was all in-house. They even treated their own telephone poles. So something like a practical survey of various types of preservative treatments for wood was in the remit of Bell Labs just like the physics of a vacuum tube. Almost everything in science was in the remit when they had such a broad mandate. The Bell System had elements that almost resembled a kind of state within a state. (Part of why it was killed off -- antitrust violations.)

"the" Bell Labs was effectively gone by the 1970's anyway. So the Bell Labs described in this article was "the" Bell Labs

Totally agree! DOE is way underrated. Once you’ve had to run real experiments (especially at scale), you really appreciate how much time and money a good experimental design can save. It’s one of those areas where a bit of math makes a huge practical difference.