From the front photo you can see that the
connecting traces are very
tight. However, within proximity of the ICs, they are
inferable, but it's
not always obvious. I know this because I've looked at an Apple-1 a few
times and pondered how challenging it would be to discern the traces
undeather sockets. If you look at the socket on the far left of the
board, right above the Apple Computer 1 wording, you'll see what most (if
not all) of the sockets on the board look like. There's no way to see
underneath without removing the socket.
A bright light on the component side of the board shining at the IC in
question will sometimes allow the component side traces to be seen. I
really can't imagine the Apple I board being hard to reverse engineer
althought it would take some time to do it.