Many of your errors can be solved by calibration - your laser trimmed ics rely on this! But obviously calibration for a production device is a pain but in many cases a necessity. Devices like digital pots can help to automate the calibration. I deal a lot with strain gauging - there's so many sources of error the only way is to calibrate them out. The trick is to know your sources of error and to quantify them before trying to calibrate them out. Take for example a thermocouple - its well known you have to have a 'cold junction' to compensate for the thermocouple at the terminals (that is the cold junction).