They want unemployment to be low so they can keep wages and salaries suppressed
High unemployment helps employers because they can put pressure on the workers, who are less likely to find a job with better conditions or at all.
The fact that low unemployment is associated with stagnating wages these days is a massive failure of the capitalist system. It means that the situation is deteriorating and some of the levers cannot be used. There is no way out without pain.
So my reasoning was "if there are not many unfilled jobs, it makes it tougher for people to find work, meaning the unemployment rate is low" which of course does not logically follow
My mistake
There are signs of upwards wage pressure in the last couple of years, we’ll see how sustainable that is.
Increasing automation and therefore productivity means an increase in profits to the owners, not a drop in prices, except in the most competitive industries.
Unemployment is already extremely low. There aren't tons of Americans waiting to step into these jobs. If unemployment were 10% that would be a different story, but we're close to full employment. So instead of the jobs going to Americans, the produce rots in the fields, and prices go up.