If you ask any company about their SEO for their website, the question will likely be ignored and pushed to one side, or a generic answer will be given. So, why are SEO techniques such a big secret between companies.
Truth be told, companies are always in competition with each other. Sharing your SEO secrets for placing your website near the top of search engine results is like a chef giving out their secret ingredients. It is just never heard of.
It is likely if you work for any website development company that you know of many SEO techniques from all different companies. But, you have likely signed a contract where you cannot share these ideas if you leave. Every company wants to protect their business, which is why you will not see them discussing their SEO services.
There is the opportunity to hire SEO experts to help you to boost your SEO, but you will never learn the techniques from other brands!