Interestingly this already does happen a lot, but usually in more complex and high-value B2B contexts. ISDA Master Agreements, (G)MRAs, GMSLAs, LMA documentation, EFET General Agreements, Incoterms, etc. The fact that it is more common in B2B contexts than B2C is IMO a reflection of the power imbalance in the latter as it benefits a large corporation to have consumers contract on its terms. Where there is standardisation in consumer contracts it is usually driven by law or regulation as the market isn't otherwise incentivised do it. For example some countries do have template tenancy agreements published by the government or a regulatory body.