The issue is not so much inspectors as it is the light slap that fines from OSHA make up.
Currently the top fine for a single issue is $70,000. Unless a criminal conviction is obtained, companies have often decided that its cheaper to risk paying the fine. Add in the huge bonuses often available for bringing in a project on time, and you have a recipe for disastor.
If there is a complaint to OSHA and its life threatening, there will be an inspector on site within 24 hours. The problem is that workers are no more interested in job safety than many companies are. I fight that mindset on a daily basis.
Crane work has a huge number of regulations. But most of them involve training and rigging that are not commonly visible to casual inspection. So they can get away with a lot.
OSHA has pushed its focus towards trenching & excavation, and made that a top priority. Consequently, although it seems the other areas have suffered, there has been a marked drop in both fatalities overall and in excavation work. Excavations are some of the most deadly work zones. Other areas have more accidents, but none have the fatality rate that excavations do.
Also, there are more OSHA inspectors now than there ever have been. Tax cuts or not, there have been additional inspectors added most years. But its still up to the companies to make sure they have a safe work site.
The best thing that could be done would be to make a multi-tiered fine system. Huge companies should be fined on a much larger scale, to make it punishment. But small companies should not be put out of business for recordkeeping errors.