Licencia de Obra Menor

Has anyone ever applied for anLICENCIA DE OBRA MENOR, I’ve just had a look at one and it’s giving a price of 25€/square mater for tiling. This surely doesn’t mean that you pay 25€ for everysquare meter of tiling that you would do to retile your bathroom or Kitchen, as this would be dearer than doing the job yourself. If this is the case then I am sure a lot of this work would be done without informing the authorities, and therefore no taxes being collected. Or have I completely misunderstood this and the authorities take a small percentage of this 25€. If I was tiling a room 25 square meters I would have second thoughts about doing the job if I had to pay 250€ therefore everyone would lose out.