If the world was perfect you would be correct on thinking £200000 a year but in the real world unless you are tiling football sized fields every day 7 days a week I would agree, unfortunately most jobs are smaller also include niches etc and consist of precision cuts especially as tiles are getting bigger and bigger.
Then you have to deduct grouting time included in the price, time and costs spent quoting, admin time, wear and tear on tools, / vehicle costs, public liability costs, accounting fees, etc etc.