Aside from the fact you associate human life with money, which is horrible in itself, you didn't understand that every person wrongly executed was found guilty beyond reasonable doubt (obviously), then later found innocent. You also don't understand that the legal system is expensive what with speaks and the cost of lawyers (you know that money thing). It is often more expensive to execute someone than imprison then for life. See the attached information which can be found easily.
Granted, everything is more expensive in some countries than others but you can't look at people as economic goods.
As an aside, in Thailand, for instance, arresting Burmese for crimes committed by Thais is not unusual.