Majority of Jews during WW2 died outside of death/concentration camps [1]. Army, police or SS rounded up Jews in some majority-Jewish town or village, took them to a nearby forest, forced them to dig their graves and then shot everybody. Rinse and repeat. Sometimes non-Jews helped, or even did it without Germans. Sometimes they helped Jews and were killed with them. Sometimes Germans just killed everybody. Sometimes they had list of people to kill for political reason (for example university professors, priests, politicians, army officers, teachers etc. were targeted no matter their ethnicity).
Vast majority of Jews before WW2 lived in small mostly-Jewish towns and villages in eastern Poland and western USSR. It would be inefficient to move them to death camps, also you could steal from them when you murdered them. Win-win.
There was no need for technology, nazis weren't checking the papers or bothering with recording anything. There are thousands of mass graves near formerly-Jewish towns. Non-Jewish population was mostly helping to point the Jews because they were competing for food and resources during harsh occupation conditions, and besides Germans were mass-murdering non-Jews too, just as a lower priority. And if you protested you were Jewish too, right?
According to Timothy Snyder the main difference between countries where high or low percentage of Jews survived nazi occupation wasn't antisemitism but how much pre-war institutions were preserved. In countries where the nazi occupation was negotiated and the rule of law was preserved - it took months to confirm these people were Jews, move them to camps, sort them, etc.
In places like eastern Europe - where Germans just destroyed everything and law was practically non-existant - why would you bother with all of that? It was basically 4 years of the Purge. 1/6th of the population disappeared in Poland between 1939 and 1945. Jews were about 10% of pre-war population.
The involvement of IBM was shameful, but it wasn't necessary. The only technology nazis needed was firearms. And they could probably do it with knives and sticks if they really wanted - like in Rwanda. Or like in USSR or Communist China for that matter.
[1] https://en.wikipedia.org/wiki/Bloodlands