Most of the courts did look at the evidence provided to them by Trump's lawyers and found them lacking evidence. You should read some of the decisions, where they talk about the affidavits and why they don't show any real issues. Yes, there were cases that were dismissed for "procedural" reasons, like the Texas case where they went directly to the Supreme Court, but those were not filed by Trump's lawyers.
Next, since you don't want to trust the courts, then you have Trump's DoJ, where AG Barr was tasked with investigating all the claims of election issues. Barr handpicked members of the DoJ and FBI to investigate and they found no evidence of widespread voter fraud, nothing that would change the election results. If that isn't enough, Homeland Security -- again, part of the Trump administration, with the leaders handpicked by Trump -- found no major election issues, proclaiming it the safest and most secure election in US history.
And, just to add a bit more, the International observer groups (also Pres. Carter's observer group) -- all organizations that know what to look for, having worked fraudulent elections -- found no evidence of widespread fraud, they declared the election was run properly and well.
The evidence does not support claims that the election was "stolen" or had "massive fraud."
