A concrete slab ignores all the requirements of Sustainable (Urban) Drainage Systems, SuDS.
Curious about this too.
Ultimately for our front I'd like a mix of paving and recessed square cut outs with a mini non-grass lawn and thymes. But as we're on a slope on a slope I'd worry about water run off.
just had a thought, how permeable/environmentally OK is that? does it not shed rainwater?