The effort of fabricating yourself dense CMOS integrated circuits, instead of giving your design to a foundry, to have it fabricated there (where a malicious foundry could modify the design), is huge, even when you do not want a state of the art technology (which would require billions of $).

Here, the description of how an end user could verify what a die contains is intended to guard not only against the possible modifications done by a malicious foundry, but also against a dishonest designer, who could claim that the chip contains something, which is shown in documentation and in the part of the design files that are open source, but the real design could include something else.