Keep in mind that canonical tags, redirects & noindex meta tags all have unique SEO consequences; they aren’t interchangeable.
A content team may have access to some but not all of these, so implements one as a substitute. Developers may not understand search engine implications when making choices during a redesign. SEOs can help here.
A canonical tag is used to define a main page, representing a set of duplicate or very similar pages, for search engines. This still allows the user to access other versions and may be needed when you have different ways of categorizing or filtering a page. This aggregates link signals to the main page if your canonical makes sense.
A redirect removes the page for both search engines & users, taking visitors to a new page. This may replace old content or represent a URL change. This also aggregates link signals so long as the redirect is relevant.
A noindex removes the page from search engine results, eventually having them not follow it. Users can still access the page. Apply it to non-SEO pages since link signals will then spread among fewer pages on your site.
Search engines attempt to not have mistakes harm your organic search results, yet they may fail. For example, Google ignores canonical tags if it finds enough unique content. Canonicals should not be considered as “soft” redirects.
As a final reminder then, use these directives carefully!