Pushing back would show solidarity between the two. Having the two types of employees resenting each other only aids the employer obviously.
Like, obviously the Field techs can't work from home. But you have to get to the core of the issue. WHY do people want to work from home?
- Time to take care of at home work. Scheduling maintenance, doing chores, etc. Once you are off work you still have work to do. If you could do that work while also earning your living (say, running laundry between work tasks) it frees you for more personal time, creative time, leisure time.
- Outside of the panopticon. working in an office is like being in prison within a panopticon. Everything about your existence is observable, and scrutinized. From how you dress to how you talk etc.
- No commute. Let's be real everyone at this business is paying out of their own pocket to commute to work. The field text probably do not get paid for their commute to the field and if they do it may simply be a mileage reimbursement.
You get the idea. This will obviously be unique to your place of employment but if the two groups of people sat down and talked about why they want to maintain their work from home, they might find that the reasons they want it are things that the others would want as well. Then you can collaborate on how to achieve each of those items for everyone.
While the office workers may work from home you may be able to identify that the field workers should have the ability to work less days a week. Worst case they may be able to work longer shifts per day so that they may have the day off later in the week extending their weekend.
Ultimately the thing that working from home gives people is freedom. Freedom to accomplish tasks that are required as a result of owning a home, renting a property, or busy simply being alive. Because outside of work you have your personal work. Buying groceries, yard work, car maintenance, house maintenance, personal development, medical checkup requirements either mental or physical. Every hour spent on the clock locked in an office is an hour you cannot use to perform those tasks.