I have some limited experience of Spanish electrics. I have posted many dodgy pics of dubious installations, some of them very funny, some a bit dire...it's not unusual to see outside lights run in bell-wire with choc-block connectors run over gardens and open to the elements. However, the electricians I have had in my house there have been very professional, (except they use wire-nuts!) and they do not charge much either.
All circuits are radials. That's good, in my opinion, and it's all singles run in conduits buried in the hollow block walls, with access plates at recessed JBs in every room.
It's true that many circuits can be a bit haphazard, but the internal wiring is generally good. My place has a 12-way CU, and it's a small, 2 bed apartment, with separate radials for washing machine, hob, kitchen sockets, other sockets, water heater (immerser) lighting (split over 2 circuits) water pump, main switch and "differential"...
The electricians turn up same-day, charge about €17/hour (last bill I had was 5 years ago, so may be more now) and do a good job...and don't send their bills in for months!
However...many homes have a very limited supply, so 100A is rare in apartments, thus if you want a big supply you may have to wait, or not get it at all, due to unavailability on the network.
I asked for a bigger supply some 10 years ago, and the supplier Gesa_Endesa, insisted that I had to install heavier incoming cables and a new CU. That was done...the supply incomers are in conduit under the concrete and tiled floors, but they pulled in a new supply in less than a day.
I guess, in summary, the Spanish do have many old supply issues and many, many dodgy bits...but they have modernised a huge amount recently, so I would be happy to work on their systems should the need arise.
My "tame" electrician always gets a box of Wagos from me when I call him...he loves them!
Good electricians...dodgy networks...but improving all the time. It's a great place to ply one's profession...new installations are inventive and serviceable, and they are bang up to date in many ways...just a bit amateur when it comes to outside work.