Agreed, but when you get the GPS unit and the whole of the UK maps at 1:50,000 OS Landranger (identical to the 'normal' paper maps)
Showing all footpaths, contours etc etc for £70 all in, for me its not a big problem.
If you want to go down to 1:25,000 then yes - you need to buy their maps but their 'county' maps at £30 ish are 'not over the top'.
I managed to find a second hand 'Platimum' SD card (on ebay) that has from Liverpool to Hull and everywhere South at a scale of 1:25,000, and 1:10,000 (selectable) for £70
https://www.satmap.com/gb-platinum-south.htmlI am not suggesting my choice was the best option, but as a 1st GPS, on a budget., it seems to 'tick all the boxes' for me.
Other choices are available.