As other posters have mentioned above, the technology itself is not "invented" on the spot by the capitalist himself, the capitalist is not a magician who can make things show up out of thin air, the technology and the related improvements are put in place by the workers. You pay workers less they have less and less reasons to think about improving the technology owned by the capitalists. It's as simple as that.
Uh, which is why pay for IT/programmers is high, and pay for sales clerks is low. It doesn't matter if your low end worker is doing half as much if technological productivity gains increase 10x.
I've thought that that would be one of the responses, and you're partially right, of course. But in the grander scheme of things better wages for workers (including sales clerks) would, among other possible outcomes, also increase the "talent pool" (for a lack of better word) from which future capitalists will pick their "inventors" and "technicians" 15-20 years down the road.
More to the point, under the present conditions only the kids of capitalists themselves and the kids of some privileged social strata (like IT people's kids) are free to fulfill their intellectual potential 100%, because they don't have to worry if their parents have enough money for rent/putting food on the table/education, and as such they can spend their late teens - early 20s (when they've grown up a little) trying and playing with new stuff, studying whatever university courses they feel fulfills their intellectual potential etc, and not having to worry about finding a McDonald's job because their parents have left them with nothing. But if you pay all the workers a little more then their kids will also be able to follow the intellectual subjects they're really interested in instead of studying and learning only to get a job, any job, in order to pay down the future student-loans faster. These people would very rarely be interested in inventing new stuff for their "capitalist" owners or in becoming entrepreneurs (which it has been proven that it's good for capitalism, I mean, there being more entrepreneurs).
The same argument (only much better put into words) was made by J.S. Mill when he wrote about why women should be fully allowed in the workforce on the same level as men. He found it really, really inefficient that about 50% of the human population was taken out of the intellectual pursuits, which for us, as a species, means that we get to have 50% less inventors/great artists/technicians.
Why would let say business owner care about the increase the "talent pool" 15-20 years down the road ? By then maybe the technology is improving to the point you need even less talent.
Your second paragraph, why would the business owner care about their workers kids ?
> Why would let say business owner care about the increase the "talent pool" 15-20 years down the road ?
Because said capitalist presumably has kids, and he wants his kids to have a bigger talent-pool from where they can choose their future employees so that the company can continue to prosper. But you're right, nowadays "business owners" doesn't mean "capitalist" (or a bunch of capitalists, let's say maxim 3 or 4), it usually means some anonymous pension funds which appoint administrators (i.e. CEOs) to run the business for them. Of course that those CEOs don't have any incentives to look forward in time because their kids' future success doesn't depend on what their present company is doing. Schumpeter decried this phenomenon as early as the 1930s, and predicted that will "help" with the demise of capitalism.
> Your second paragraph, why would the business owner care about their workers kids ?
I hope I answered this in the previous paragraph. In short, the business owners' kids will need to have employees on their own (and good ones at that) and relatively speaking prosperous clients. If you don't care about the kids of today's workers then you're reducing both the numbers of your kids' potential very good employees and prosperous clients.
