Because people voted for Brexit.
Prior to Brexit you had a right to watch TV services from your home state/country in any other member state, however this limit should be seen one of the benefits of Brexit -- and if you voted for Brexit then that's one of the things you would have been aware of at the time of the referendum, if you voted remain then theres not much you can do
As far as i know the Terms and conditions of Now TV should state that its only for use in the UK .
If you want to watch something, then there should be legal options to stream it in Spain on a Spanish subscription service
See the post from @chilli2 since Brexit any UK subscription service will NOT work outside the UK.
This link will cover it nicely.
https://help.nowtv.com/article/can-i-watch-abroad
I see this all over Now TV - subscription services will not work outside the UK. I’ve been going to Spain for (fairly long) holidays for years. I pay for Now TV when I am not in the UK. I pay a licence fee to watch UK terrestrial TV, when I am not there. I pay for Netflix and Amazon Prime and have no problem at all using my accounts in Spain. So why does the EU allow some services and not others? And why does every bar in Spain show Sky Sports when I am having to pay for a service I can’t access? By the way I voted to stay in EU and have never understood people who supported Brexit
This is purely down to Comcast not signing a deal with Paramount to do the joint venture in the UK. In Spain and other non Sky territories you have SkyShowtime, which can be watched in the Nordics.
The EU will allow native streaming services like Movistar+ etc across other EU countries. Whereas Netflix, Amazon and Disney+ are set for the global market and will fully permit it in any country where it exists, albeit a vastly different library.
PS, my parents live in Spain so I have access to SkyShowtime and Max thanks to a VPN. My dad voted to leave and my mum voted to stay, everyone I know apart from my dad all voted to stay.