> I don’t see why software should receive special treatment when 99.99% of software engineers/developers are not in any way engaged in what might be considered genuine scientific research and development, which R&D tax advantages should be reserved for.

Why? There's a clear relationship between R&D spend and economic growth. This is including R&D spend on non-scientific endeavours like commercial products + processes, which the majority of non-maintenance software work falls into.

Estimates vary, but I've never seen a cost/benefit analysis of unrestricted R&D that finds anything lower than a $2 return for every $1 spent in unrestricted R&D.