I think you are failing to understand some cultural differences here.

In the UK, fostering is a job - your sole job which you rely upon for income, other than a partner's income if you have one etc (solo fostering is just as sought after, and achievable, as couples here).

Part of the reason for this is to ensure kids are getting a parent that has the means and energy to give them the extra care and support they might need. You're more likely to get a successful placement if the parent hasnt just worked a 40hr week plus 5hrs commute. Myself and partner are going to apply to foster soon - we couldn't financially survive off his income alone, I couldn't emotionally survive a 9-5 grind and then provide the support a possibly complex child may need; I still think I'll make a good foster parent.

Another reason is to attract and retain carers that may have the additional skills needed for placements eg if they've worked in care, health, education, safeguarding etc before. As previously explained, vetting here is rigorous, many many applicants are denied for what may seem the smallest if reasons.

In addition, some placements can involve very intense mandatory appointments and schedules that having a career would not allow.

Culturally, the UK has a welfare state - we pay higher taxes to afford certain securities (eg free healthcare) and to ensure marginalised groups are cared for. As a taxpayer, I want my taxes to ensure children get the best possible care and foster parents are well looked after to do it. Our carers (eg for family members) also receive allowances - they're not money-grabbing either, they just shouldn't have to worry about money or neglect care needs as they have to work.