The thing is, if the company offered 45 days of bereavement, every one of these workers would take all 45 days every year. I was the engineering manager for a company, and we offered a certain number of sick days per year, and all the people who worked in my department took every single sick day, every year. How times have changed. My father was a banker, and in 35 years, never called in sick.
I'm not 100% sure this would happen. Once established rights are in place you find people don't - generally - take the biscuit.
I have pretty much unlimited sick pay - I am only off when I'm sick. I have 35 days annual leave in addition I have the 8 bank holidays off. I am almost always pressured *to take* my full leave at the end of the year.
Once the culture is there you find people only use what they need.
So, respectfully, I don't think you're right in thinking that 45 days sick days would be 100% taken by 100% of workers.