Once local worker market is exhausted and employers search overseas the demand supply equation changes, the US has the highest paying jobs generally so what is a 15-30% before rate salary in the us is a high salary overses.

Yeah..... But the most common occupation listed is for it/computer science which is a already a highly saturated labour market. There are plenty of highly educated and experienced locals to hire from, companies like amazon just don't want to shell out the money they were spending when people were aggressively headhunting during the pandemic.

There is the clause that these workers must be paid within the averages of their position and there are examples of companies breaking that. Thats an enforcement issue and not reflective of the program.

But the DOL is responsible for enforcement and the program. How can it not be reflective of the program? This study goes into depth explaining how corporations take advantage of H1b to harm the labour market.

No, the rule is that it must match the "prevailing wage" which is the average amount of is the basic hourly rate paid on public works projects to a majority of workers engaged in a particular craft. Public work is usually significantly lower than private work.

"The two lowest permissible H-1B prevailing wage levels are significantly lower than the local median salaries surveyed for occupations. The two lowest H-1B wage levels set by DOL correspond to the 17th and 34th wage percentiles locally for an occupation. This translates into salaries that are significantly lower than local median salaries—17% to 34% lower on average for computer occupations (which are among the most common H-1B occupations). H-1B employers can reap significant savings by selecting one of the two lowest wage levels instead of the Level 3 wage (the median, or 50th-percentile, wage) or the Level 4 wage (above the median, at the 67th percentile).

h1b workers are being brought on as temps for specific projects so their salaries are below the average for what that company pays for devs overall.

Companies are hiring them from 3rd party outsourcing firms as a cheap labour pool, not as temps for specific projects.

"Outsourcing firms make heavy use of the H-1B program. Half of the top 30 H-1B employers use an outsourcing business model to provide staff for third-party clients, rather than employing H-1B workers directly to fill a special need at the company that applies for the visa."