There's a window cleaner in an area of bungalows not far from here who only does bungalows. He has a bucket, applicator, squeegee, a few cloths and a 7' pointer and that's it, no car or van or wfp or anything else and he walks from job to job.
When he does a £10, £15 or £20 job or what ever price, it's 100% profit and his overheads are a few cloths and bits maybe once a year.
He's been window cleaning for about 30+ years and has quite a substantial round all in one area. In some ways I envy him as his life working is so simple and uncomplicated.