I fell there is far more risk of someone poking their fingers in
the fitting while it is on, then there is of a fire breaking out
how often are [regular GLS] bulbs changed compaired to how many
times fires break out in a house?

Yes, but the shock is rarely fatal or injurous, just painful and
embarassing. The nature of the fitting doesn't lend it to maintaining a
solid grip on you long enough to cause electrocution.

And quick frankly, if you electrocute yourself changing a bulb, you're
probably capable of removing yourself from the gene pool in a much more
spectacular fashion.

The reason not to install an RCD is because lights failing is a demonstrable
and measurable cause of death either during house fires, or from sudden
darkness during a dangerous task (such as operating machinery, or balancing
on ladders). Electrocution from changing light bulbs doesn't figure in the
statistics.

Christian.