Stating the obvious, wfh versus non-wfh is only a debate about work / tasks that can be performed physically either in an office or in a home.
We have already discussed the “taking the piss” issue to death and that is really about the individual concerned rather than wfh or non-wfh.
OP’s original query is about folk doing wfh (rather than taking sick leave or a holiday) when they have a domestic issue that arises. That could be an ill child, the person is sick themselves, awaiting a delivery, or possibly just a late night.
Always provided the work gets done (or the hours caught up), wfh seems ideal and represents a good flexibility for both the employer and the person involved. The sick day / holiday alternative is a lose / lose for both – the work doesn’t get done or is delayed or needs to be dealt with by somebody else and the person involved is not really benefiting from his / her time off.
For sure, there is a need for common sense and responsibility – so try not to schedule that furniture delivery for a day when we really, really need you in the room at the office to make a major presentation to our most important client.
But, that aside, I would have no hesitation in suggesting an employee wfh to accommodate such issues. Frankly, I regard that as plain, sensible and caring management. In practice, I have found that flexibility often then works both ways: when the business is “under the cosh” to meet important deadlines, employees are much more willing to put in the extra hours, defer personal time they had planned, etc
The next stage to consider is when “unplanned” wfh seems to be happening too frequently.
If it is due to too many late nights on the town then there is an issue of whether the person is capable of doing the job. However, that same issue applies whether the person seeks to wfh the days after, takes a day off, or struggles into an office anyway but isn’t too productive when they get there. Personally, in the first instance I would sit down with the person and ask if they had any issues or problems that we could perhaps try to help with. For sure, if it is just immaturity or lack of responsibility then the employee is likely taking the piss with wfh but the much bigger issue is non-performance and that same issue would still be there if the person took leave rather than claimed wfh or wandered into the office anyway but got little done while he / she was there.
If frequent, “unplanned” wfh is happening due to personal sickness, frequent illness of a child or other relative then I would definitely be in “how can we help” mode. On occasion, I have found it is possible to restructure the overall work for the team to help. For example, move to more of a planned (and increased) wfh status for that person; direct more of the less time-sensitive work to the person; incorporating knowledge of the impact of the issue in terms of how we manage things as a team; and (with the person’s permission) explain to the rest of the team some of what the person is coping with.
I have never encountered any issues of resentment from the rest of the team – more an appreciation that the team will be looked after; a willingness to help a colleague; and perhaps also the opportunity to pick up more interesting work.
For sure, there have been occasions when the non-work demands have been such that the person has eventually migrated from a 5-day week to a 2-day week or has needed a leave of absence. Equally, this might not be possible for all roles.
However, I see wfh (and increased wfh) as a potential part of the solution that benefits employer and employee.
Finally, OP raises the question about “pre-planned” wfh with a couple of examples.
The idea of both parents doing wfh while raising their new baby actually strikes me as a great idea. The fact that both parents are there mitigates any issue of baby needing attention at an inconvenient moment. It is also going to eliminate last-minute absences etc that might otherwise arise if they were both working in offices 5 days a week. So, they have the chance to raise and bond with their child but are still as productive as ever (if not more so). Why would that ever be a bad thing?
With regard to senior staff doing wfh. I really do not agree that this is leaving less-senior staff to do their work as well their own and picking up the problems. The senior person – whether in the office, at home, on a business trip or wherever – needs to be contactable and also proactive in communicating with their team. This can often be more challenging in an office environment and less challenging over the telephone while wfh. The key issue in the office is the informal and social interactions, coupled with easy accessibility from both more senior and more junior colleagues. These interactions are all important too and do need to be fostered but (in the office) they can easily delay or derail tasks that should have higher priority. A “9-5” office environment often knocks this out of balance while a mix of wfh and planned in-office time enables balance.
If the senior person doesn't perform his / her responsibilities well while wfh then he / she likey doesn't perform them well in the office either. Its the person - not whether they are in the office, at home, in a hotel room or anywhere else.