How many levels of red tape does it take to get to $50k per sidewalk curb ramp would be my question more than anything.
It should be possible to find out and compare the cost in different US cities.
Here's a service in a medium sized town of Colorado:
"Large or Complex Projects - extensive curb modifications or custom installations can cost $1,200-$3,000 or more. These projects often involve additional planning, permits, or structural considerations, which can increase overall costs. Many jobs are completed within the lower part of this range.
Full Replacement - complete curb or sidewalk replacements typically start around $3,000 and can exceed $5,000 for larger, more involved projects. These are less common and usually reserved for significant repairs or upgrades, with most projects falling into the lower to mid portions of this range."
Quoting an article about sidewalk replacement in NYC (a city generally not associated with low construction costs):
> ADA or Corner Adjustments: If you’re on a corner, curb ramp or flag work might add $500 to $2,000.
https://www.onrec.com/news/news-archive/nyc-concrete-sidewal...
This is a poster child for the Law of Unintended Consequences.
See also "minimum wage".