A small clique of companies make the tabulators.  Their source code is not open to outside inspection.  Feed the ballots in and hope the outcome is accurate is a poor substitute for verification.  And then there are touch screen machines that have no way to verify the alleged results.

In more democratic countries where paper ballots are counted by people, representatives of the different candidates oversee the counting, and it works well.

The "Cross Check" system was also used to purge a million minority (aka Democratic) voters.  Investigator Greg Palast has done excellent work exposing this, he got a copy of the database!  Legitimate voters from the rolls in several states - voters with the same first and last names, but different middle names, were claimed to be the same people (in different states!) and then purged.  This is the alleged basis for Trump's claim that millions of non-citizen supposedly voted for Clinton.