Mostly that you're asking the developers to become experts in software testing and verification, in addition to their existing knowledge. If you have good mento

Mostly that you're asking the developers to become experts in software testing and verification, in addition to their existing knowledge. If you have good mentoring & examples & guidelines, then everybody can learn and move along roughly the same path. That takes time and effort to set up, so in those small startups you're likely to see wildly divergent approaches to testing + the friction when people think they should standardize, or when they actually do need to, or when people switch teams.