Flexible working - what are you so afraid of?

I'm not job hunting, I'm very happy freelancing but I am regularly called by recruiters looking for people with my skills. One local employer has been looking for over 4 months for someone with a background in tourism marketing to manage their social media; I've lost count of how many times I've been ask if I'm interested. I would be, but I've already decided against the 9-5.

I'm open to opportunities but if I'm going to head back into employment there needs to be some scope for flexible working, and why wouldn't that be an option when you work in online marketing?

It's so depressing when I ask if the employer would be open to flexible hours/some home working and the answer is always no! What are they so afraid of? There seems to be a huge element of mistrust of people who are able to be productive outside of an office environment. Surely it comes down to whether you can get the job done and I can assure you, being in an office 9-5 does not, in anyway, get my creative juices flowing or make me more productive.

How many good candidates are these businesses missing out on because they're tied to the 9-5 regime?

I look forward to the day I see a job advert actively seeking flexible workers, it may even tempt me to consider employment again... maybe.