Pitching rates that I have read are optimal for homebrewers in texts (Designing Great Beers, Ray Daniels is awesome, here I paraphrase) range at 200-400 billion cells for 5 gallons. The problem with that is that with commercially avqailable homebrewers yeasts, getting a starter that big would have to be in gallons and thats not really practical. Reduced, acceptable rates are closer to 10-20 billion MINIMUM. All this is for "normal" gravity.. say 1.050.
So to reiterate my previous point, commercial breweries have access to better toys for brewing. Including yeast. It is far easier for them to obtain proper pitching rates that will ferments in days vs weeks that we as homebrewers experience.
A lot of the things at their disposal are easily (depending on your dedication and technical aptitude) reproduced in the home setting. Sometimes they are just less practical and don't make that much of a difference. I.E.: waiting 4-6 weeks for total fermentation vs 1-2 weeks. As it is now, my pipeline is bigger than I can possibly want to drink, even with the help of a few friends. And I'm no big timer.