The lack of transparency of the UK government is a disgrace and needs to be challenged. Covid illustrated that very clearly - SAGE discussions were kept secret here in the UK, while their equivalents in other European countries had public minutes of every meeting. Ireland published the whole thing online.
That UK democracy has many very undemocratic elements (see also this current competition to become the new PM) is not an argument for anything other than that those undemocratic elements need challenging. Your solution seems to be that we should just give up on the aspiration of democratic accountability altogether.
Secrecy is certainly part of the scene, and has implications both for accountability but also other stuff such as revealing how power is spread or concentrated, what calculations are part of the mix, whether those calculations are unpalatable if revealed to the public, etc.
As
Pickman's model has already pointed out, there are actually a large number of SAGE documents available online, including ones that are labelled as minutes. I wouldnt really call them full minutes, but then I would say the same about Irelands NPHAT documents too. They are both more like meeting summaries than actual formal minutes, eg often avoided revealing what specific individuals said.
Other relevant factors are that in most countries including the UK these bodies were involved with making recommendations rather than final decisions. Countries certainly varied in terms of how likely their elected government regimes were likely to turn those recommendations into policies without exception or delay, and the exact extent to which the bodies had formal decision-making capabilities, or how politically unacceptable a government going against them would have been considered to be by the opposition, the press etc.
Another key variable in terms of transparency is how quickly the information from key meetings is made public. When it comes to headline decisions and policy implications that are acted rapidly upon, the delay may be incredibly short, and the key March 2020 period of the pandemic was a good example of that. But when it came to the detail, there is usually some lag, especially when notes or minutes from the previous meeting have to be signed off by the group in a subsequent meeting. Having a well enshrined right to info in a timely fashion can help bring consistency to this area and reduce the temptation for political shenanigans. The UK was a poor example of this because SAGE publications were belatedly made public in a rather variable fashion, especially when it came to more sensitive topics. And even much more than a year intot he pandemic, it was not unusual to see some documents not being published for months, and some SAGE documents coming out very quickly if they involved some new policy the government had actually decided to finally implement.
I did look into Ireland and their key documents from the important March 2020 period. Some expert subgroups documents didnt start being properly published until April or May of that year. And there was an interesting gap in publication of some of the most important NPHAT meeting notes. For example their March 11th meeting was an important one, but using wayback machine I established that that meetings documents did not appear on the site until some time between April 13th and April 22nd 2020. However unlike our SAGE, their NPHAT was also responsible for daily public data and narrative documents via press release, so certain details did emerge in a more timely fashion or, like the UK, were obvious due to the policies government adopted. In the UK we were sometimes 'treated' to such things via leaks to the press instead, another kind of information control and selective filtering that belongs in a broader discussion about this stuff, and can serve as a more 'flexible' UK equivalent to mechanisms for provision or restriction of information in other countries.