Assumption of Innocence

Recently a man extradited to the US on charges of illegal arms trading has changed his plea to 'Guilty'. This after protracted legal arguments in court to stop the process. This cannot have been cheap whoever bore the costs. Why wasn't it possible for him to plead 'Guilty' from the start and save all this money and trouble? This is an abuse of the Assumption of Innocence concept that says that everyone is innocent until proven guilty.
A convicted murderer later in prison admitted killing another person and led police officers to where he buried the body. Despite this the Crown Prosecution Service (CPS) cannot convict because the police officer in charge did not follow correct procedure. Why should it matter if the criminal owns to having done it, the police know he did it and the CPS know he did it? This is an abuse of the Assumption of Innocence concept.
Two men are arrested, 'red handed' outside a public house they have just robbed by two policemen. They had, in their possession, a sock full of coins stolen from a gaming machine. The judge ruled that because the sock, part of the evidence, could not be found on the day of the trial the men couldn't be convicted. This is an abuse of the Assumption of Innocence concept.
Is it not time to stop pandering to the legal profession and their extortionately expensive trade and challenge the concept that in every case innocence is presumed unless proved, to a ridiculous degree, otherwise. There ought to be a means of bypassing the legal necessities in such cases, especially where the costs are met out of the public purse. Perhaps a special Home Office Order signed by the Secretary of State. Furthermore it ought to be possible for courts to be more lenient for an early guilty plea. By the time a case comes before a court the CPS should have satisfied themselves of a conviction. If the evidence is compelling a plea of 'Not Guilty' should attract double the usual tariff if the case is proved. You'd imagine that the legal profession would be keen to help because at the moment it all looks a shambles and the whole lot from the judge down seem to be money-grabbing charlatans.