Rather silly question - perhaps someone can help: I get a mechanic to repair my car; he charges me for labour, and VAT (20%) on top. The VAT he charges me, he

Rather silly question - perhaps someone can help: I get a mechanic to repair my car; he charges me for labour, and VAT (20%) on top. The VAT he charges me, he pays that to the Government. I render my services as a software engineer, and I must pay income tax (~40%), and not VAT. How's my income different to the mechanic's income w.r.t. the kind of tax we pay? Or does the mechanic also pays income tax additionally?