You underestimate the CPU power needed to do this. The Netherlands has a population of 16 million, by comparison Google voice has about 1.4 million users. This is an order of magnitude difference. On top of this they only transcribe voicemail not all calls. What is the ratio of calls to voicemail?

Transcribing all voice calls to text in the Netherlands computationally could easily be two orders of magnitude more difficult than Google voice.