The latter is quite close to reality, indeed. State and regional bureaucracy offices typically open only 5 hours, from 9 to 14 (their workers work some more, but typically no more than 7.5 hours in theory, and probably less in practice) which makes them really inconvenient as you typically have to split your workday to go. And in many of those they work very, um... relaxedly. With long coffee breaks, smoking breaks, random breaks... but it's something specific of these workers, the rest of Spain doesn't generally work like that.
Bureaucracy is actually the single thing I hate most about Spain. I'm a professor at a university and the sheer amount of bureaucracy is staggering, asphyxiating at times. In fact it's a relevant factor making me work longer than I should as too much time is spent dealing with that. In industry most people don't have to deal with much bureaucracy, though, unless they're company owners or self-employed.
In industry, people tend to work long hours: there is still a culture of presentialism with remote work being frowned upon in many companies, suboptimal traditional work timetables with a long lunch break make many people return home way too late, and the threat of unemployment (not so much in the tech sector) and the need for money in an economy with modest salaries and high housing prices makes workers accept lots of (paid or sometimes unpaid) overtime.
If you're seriously considering moving, maybe it's a matter of being selective (supposing you can search while holding your current job) and taking time to find a company with more modern ways, that doesn't value presentialism and overtime. There is a growing minority of companies like that. If you mention these things as priorities in interviews, companies that want workers in their posts until late in the evening will probably filter themselves out.
If you do score a good company that allows for work-life balance and provides a good salary for Spanish standards (even if it's low for American standards), quality of life in Spain is excellent. Good climate in most places, good public healthcare, amazing and relatively cheap food both in supermarkets and restaurants, good bars and nightlife, nice natural landscapes and hiking places (especially in the north), decent public transport (not stellar compared to e.g. Germany but much better than in America) and in most cities you can go outside at 3 am and feel safe walking in 90% of the city (100% in some). I have had offers to work in America for several times my salary here and haven't even considered them.