My interpretation of what this person is saying is that it would take a lot of time and cultural change for all humans (or the majority of humans) to become vegetarian.
I agree with them.
While in most societies almost any individual person can certainly very easily become vegetarian, many people around the world have no interest in becoming vegetarian and are not going to become vegetarian any time soon. Also, a significant number of people live in regions/societies where avoiding meat might leave them with an insufficient diet because there are very few plant foods available.
Focusing on places where almost everyone could easily become vegetarian if they wanted to, there would need to be significant cultural shifts for them to do so. Here are some examples of factors that might prevent people from giving up meat:
- People often value their traditions and customs especially with regard to food. The pleasure of eating familiar dishes cooked to an old family recipe, or tasting regional delicacies on holiday make it uncomfortable to imagine eliminating key ingredients.
- People might want to consume meat because of its association with wealth and status, or to affirm their non-vegetarian identity (this is notable in India where many people rarely eat non-veg for economic reasons, and attitudes towards vegetarianism carry connotation of caste discrimination).
However, with increasing awareness of the contribution of animal agriculture to climate breakdown, there has been an increase in people giving up meat and other animal products, at least in some countries. The UK Vegan Society found that
the number of vegans in Great Britain has quadrupled from 2014 to 2019. The numbers rose from 0.25% (150,000) of the population in 2014 to 0.46% (276,000) in 2016 to 1.16% in 2019 (600,000).
Note: vegans do not consume (or use) any animal products - this is more comprehensive than vegetarianism.
This has called forth a backlash, with meat producers campaigning heavily to keep meat on people's tables. It's widely known that cattle farming is the main driver of rainforest destruction and murder and displacement of tribal people in South America (though mining and other industries are involved), but these days I see many newspaper and magazine articles (often issuing directly from meat farmers) pushing the idea that meat is good for the environment and it's vegans who are destroying biodiversity and rainforests and dispossessing indigenous people by eating soya or avocados. (In case it's useful to anyone, this review examines one farm's "carbon negative beef" claims).
This backlash is a good sign - it shows that the meat market is under pressure - but it also shows that people like me who would like to see the present forms of commercial animal agriculture ("factory farming") disappear as the majority of humans who can do so stop eating animals are up against powerful interests as well as cultural traditions and personal preferences. If commercial animal agriculture is really to be stopped or immensely downscaled, I think there is indeed a long slog ahead.
However, accepting the position that all humanity is not imminently about to become vegetarian does not require us to accept that becoming vegetarian is somehow wrong or futile. Even a single person abstaining from meat-eating has a real impact. As a small illustration of this, the UK Vegan Society has a tool to tell how many animal deaths could be avoided (or have already been avoided) by the user going vegan.