I'm not a wikipedia expert but many of those don't meet their criteria for notability. Taking the first in the Canadian physicists category, I get https://en.wikipedia.org/wiki/Isaac_Abella The only non-primary source that isn't an obituary is Who's Who in Science and Engineering. He objectively doesn't meet the criteria listed in https://en.wikipedia.org/wiki/Wikipedia:Notability_(academic...
I can't find the original pre-deletion article, but the edit comments mention that Strickland was a past president of the Optical Society. The guidelines for notability contemplate this sort of thing when they say "The person has been an elected member of a highly selective and prestigious scholarly society or association (e.g., a National Academy of Sciences or the Royal Society)". There are lots of other criteria, but that's one of them, and we can recognize that the Optical Society is not in the same category.
You can say wikipedia's notability criteria are inconsistently applied. I'm not surprised. But most of these complaints amount to asking wikipedia to recognize inherent merit, which it doesn't do. Wikipedia correctly recognized Strickland's notability after the Nobel committee recognized her merit and accomplishments.
Interestingly, while responding to this I noticed that the article we are discussing here, when talking about Strickland, probably misrepresents things. The edit history on wikipedia shows an article was created and then deleted in 2014, not "just a few months before Donna Strickland won the Nobel". The Washington Post article cited in the previous sentence doesn't support that claim either. So part of what we are discussing here includes supposed facts which might be fully invented or significantly distorted by the reporter.