If you've ever asked for an overlap threshold or stair nose for a 3/4" solid hardwood floor, then the below is probably not news to you.
Overlap transitions are designed to be installed in coordination with floating floors. An overlap transition allows for the floating floor to be installed underneath the overlap piece in order to allow for the movement of the floating floor.
3/4" hardwood floors are not commonly floated, and only in the rarest of circumstances would an installer even want to consider it. For this reason overlap thresholds and stair-nosings are highly uncommon profiles for hardwood flooring molding manufacturers to make. In most cases hardwood molding manufacturers won't make overlap pieces for 3/4" floors.
Beyond even that, to make an overlap transition for a 3/4" floor could potentially require the transitions to be nearly 1 1/2" overall thick to accommodate for the 3/4" floor and the overlap piece. The molding itself would present a persistent tripping hazard to the regular traffic on the floor in question.
While overlap reducers and overlap stair nosing remain available for thinner hardwood profiles, overlap transitions for anything thicker than 5/8" hardwood will continue to be highly uncommon.
If an installer asks for an overlap reducer or stair nose to go with a 3/4" floor, they may need to reassess that installation, or they may be asking for the wrong molding. Either way, it's time to start asking some questions about that installation.
Below is an example of an overlap stair nose for reference.