The legal bar for probable cause in the US is higher than almost anywhere else in the world.
If you're saying that cops and judges collaborate to get search warrants based on evidence they both know was obtained illegally... sure? It probably does happen on occasion, but I doubt it happens nearly as much as you seem to think it does.
There is no bar for FISA courts which is essentially a rubber stamp court:
FISC meets in secret, and approves or denies requests for search warrants. Only the number of warrants applied for, issued and denied, is reported. In 1980 (the first full year after its inception), it approved 322 warrants.[27] This number has steadily grown to 2,224 warrants in 2006.[28] In the period 1979–2006, a total of 22,990 applications for warrants were made to the Court of which 22,985 were approved (sometimes with modifications; or with the splitting up, or combining, of warrants for legal purposes), and only 5 were definitively rejected.
As for probable cause they just sidestep such niceties all the time using many many tricks including buying data from your carriers and credit card providers.
If you're saying that cops and judges collaborate to get search warrants based on evidence they both know was obtained illegally... sure? It probably does happen on occasion, but I doubt it happens nearly as much as you seem to think it does.