Well said, Longford. Even though we have a car, my wife, Citlali, takes colectivos at times in San Cristóbal de Las Casas when she visits various outlying indigenous communities but then she speaks pretty decent Spanish and has some modest and limited understanding of a couple of indigenous languages thereabouts. The human interaction one might experience on a colectivo in Chiapas and, no doubt, Oaxaca, is entirely dependent on one´s language skills so if one is not conversant in Spanish and, maybe, another local language (many indigenous people in Oaxaca and Chiapas don´t speak or speak very little Spanish), this may prove problematic.
I would never, personally, opt for a colectivo over a car or a rental car (quite expensive in Mexico because of the exhorbitant daily insurance rates) for two reasons. My Spanish skills leave a great deal to be desired and I am a very large person who doesn´t fit into those infernal deathtraps and I am also claustrophobic and you would not believe the number of people they can stuff into one of those vans before closing the doors and cutting off the fresh oxygen and any escape potential. On top of those disturbing irritations , when you get to whatever village you have chosen to visit the artisan you seek, you get to the combi stop when the combi gets there after an often long and arduous journey and then it may be time to hoof it some distance to get to the artisan´s taller and then the artisan may not be there and by the time you get back to Oaxaca City, the day is shot.
Most of our great experiences in Southern Mexico have come about because we had the flexibility of our own car or, at times, a rental car. We have visited many artisans and interesting places all over Southern Mexico by personal car whether owned of rented and we never tire of that. The private or rental car also gives you the chance for serendipitous discovery along the way to your destination, The side road or village that leads to unanticipated treasures and this is especially true in backcountry Mexico.
As we all know, you only pass here once as far as we are informed. I still remember staying in a luxurious hotel in Hong Kong back in about 1980 and opting for a room with no view of the bay to save a lousy $20 Dollars. Spend it now if you have it. There are no pockets in a shroud.