Um ... these guys just weren't your average run-of-the-mill acquired slaves.
They were, in fact, long-time residents of Egypt ... born and bred in Egypt ... who were enslaved by one king of Egypt in a single generation.
To be specific, here's what the Bible says:
Exodus 1:8 Now there arose up a new king over Egypt, which knew not Joseph.
It doesn't say: there arose up a new king over Egypt, which registered the Hebrews as slaves.
In fact, the king had plans to exterminate them, not register them as slaves.
Note what Wikipedia says:
Reading the Bible, shows that the Israelites were neither captured in war, nor sold as slaves.
So if archaeologists are looking for Hebrew slaves in the Egyptian books, they do err, not knowing the Scriptures.