Why do the Gospel accounts not specify what crimes the two men crucified next to Jesus were guilty of?

Matthew 27:38 and Mark 15:27 say “two robbers” were crucified with Jesus. Luke 23:32 says “two criminals” were crucified with Jesus. John 19:18 says only that “two others” were crucified with him. At the trial of Jesus, instead of releasing Jesus, who was innocent of any crime, the crowds asked for Barabbas to be released – a known activist against Rome “who had been thrown into prison for insurrection and murder” (Luke 23:25). John 18:40 says Barabbas had taken part in an uprising. Barabbas was an enemy of the state. You can understand why Rome wanted Barabbas crucified, but two common robbers? My NIV Study Bible says this about the criminals on either side of Jesus being described as robbers (Mark 15:27): >***According to Roman law, robbery was not a capital offence. Mark’s term must signify men guilty of insurrection (like Barabbas), crucified for high treason.*** There is also the parable of the unforgiving servant (Matthew 18:23-35) who was thrown into prison until he repaid the huge debt he owed his master. Indeed, the Law of Moses was clear that any person found guilty of stealing had to make recompense to the victim by repaying more than the amount taken. Common theft or robbery could be dealt with under Jewish law. ***Pilate had sentenced Barabbas to death by crucifixion, but were the two criminals alongside Jesus just common criminals, robbers?*** If so, then there would have been no need for them to be brought before Pilate for sentencing. This was not a capital offence and could be dealt with under Jewish law. Or were they, like Barabbas, guilty of treason against Rome? We know how ruthless the Romans were – after all, you don’t get to be the biggest Empire in the world by being soft on crime. ***If we accept the NIV comment in Mark 15:27 that robbery was not a capital offence and that the two criminals being crucified next to Jesus were guilty of high treason, then why do the Gospel accounts not make this clear?***