You don't understand that there is a difference between 2 and 2.000000000000001 as far as the software is concerned?
You might not be able to see .000000000000001 but the software can.
Geometry is defined in the background by mathematics. (brep - normally covered in a surfacing class)
If the boundaries between faces are not defined identically - then the software warns that might be an issue.
Doesn't matter if the difference is visually obvious to a human .1 or completely undiscoverable to a human .000000000000001, the computer sees it as a difference and flags the issue. In most cases it is fine for the software to Knit the boundaries together (Attempt to Heal All), but in some cases it could result in a significant change of geometry. (actual significance is defined by the designer and purpose of the geometry)
Gaps are easily found using the tools in Solidworks that find them for you. If you want to "see" them easier...switch to HLV display instead of Shaded.
Any gaps between surfaces are easily seen in HLV because the edges with gaps show as a different color.
Viewing in HLV makes finding the gaps very easy. The blueish edges are not "knitted" together.
Import diagnostics also makes it easy to find the gaps. On this part, it also was able to automatically fix the problem.
Sorry but yes, it's plain as day. The single color makes it almost invisible. Try to pick that area see what it does.