Is the measurement of the carbon footprint compulsory?

No. But most of the companies, mainly multinational, are interested in assessing their Carbon Footprint. One of the reasons is that they can use it as a marketing tool, on the labels of their products. Other reason is that by assessing the carbon footprint of the company, it is possible to reduce the emissions but also the costs. They are also interested in communicating their Carbon Footprint through their CSR reports.