How accurate is the voice recognition? Even when restricted to a few command phrases, I struggle to see how this can be overly accurate when running on a Raspbe

How accurate is the voice recognition? Even when restricted to a few command phrases, I struggle to see how this can be overly accurate when running on a Raspberry Pi. I've played with voice recognition in the past, and anything less than 98% accuracy is super frustrating after a week of usage. Siri is the most accurate voice recognition software I've used so far, and even Siri regularly fails to understand some words.