Shorter Citizenship Pathway for foreign-born Spouses of British Citizens

Many Commonwealth nations have specific paths for foreign born spouses gaining sponsorship and residency. In Australia, Spouses can apply immediately with a 2 year visa that ends with eligibility to apply for Permanent Residency. The only delay beyond this is processing time. The process is the same in Canada, whereby a Canadian Citizen can sponsor their spouse for 2 years whilst awaiting their PR application to process. We do not understand why the UK insists on a minimum of 5+ years and what we consider to be extortionate fees.