> They don't have time to ...
Which is why they end up spending time on mea-culpa "we take your data security seriously, but clearly not seriously enough" emails when they inevitably get pwned by a completely predictable and avoidable SQL injection attack.
The sort of startups you describe are jokes that barley take security seriously, let alone know what a pen-test or code audit is, let alone actually do them on a regular basis.
You don't need a stored procedure to use parameters with the query lol
You can do safe parametrization with PREPARE, you don't need CREATE FUNCTION. Don't most PostgreSQL libraries handle such concerns for you, anyway?