There will never be a single standard set of financing documents, whether for seed or venture capital rounds. And interestingly, the variance in documents increases as the deals get smaller.
The closest to a standard set is the NVCA forms, but those are for larger Series A/B/C type rounds. Regardless, it seems like each firm (or fund) has their own set of custom docs based on the current and/or prior versions of the NVCA forms. So while there is general consensus to use the NVCA docs for large investments, deviations still occur.
For seed financings, there are about 4 standard sets of documents. The people and entities that put out these standard seed financing documents have done a great job balancing the interests of company and investor at a seed financing. Yet there always seems to be changes that deviate from the ‘standard’ — whether at the request of the company or investors.
Where it really gets crazy is at the incubator level. Incubator documents and terms vary greatly. Convertible Security, Common Stock, Preferred Stock, Convertible Note + Common Stock, Non-Dilution, Option Pool, no Option pool, etc. You would think that a ‘standard’ incubator set would be much easier to develop and become the norm.
Most probably want to blame the lawyers for not having standard documents (hey, why not!), but it seems like a lot of investors have different preferences which dictate changes to ‘standard’ documents.