Is it permissible to sell electronic meters to gas station owners who charge citizens excessive amounts, knowing that the responsibility falls on them and their employees, and that there is oversight from state employees?

What some gas station workers do by taking extra money beyond the price of the fuel without the buyers' consent is consuming people's wealth unlawfully (أكل لأموال الناس بالباطل), based on the Almighty's saying: "And do not consume one another's wealth unjustly" (وَلَا تَأْكُلُوا أَمْوَالَكُمْ بَيْنَكُمْ بِالْبَاطِلِ). However, if it is with their consent, then there is no harm in it.

As for the questioner's work in designing meters for these stations, there is no objection to it, because the sin is not related to his work and is not caused by it. The meter is a tool for knowing the quantity and value of the fuel, and it is for protecting the customer and the station owner from the manipulation of workers.