Whats the adjective for doing something not required but makes things easier?

I'm all for showing gratitude to another person when they've gone out of their way to be helpful or communicative, personally I don't bat an eyelid at sending or receiving emails outside of normal office hours, but certainly nor would I demand or expect a response out of those hours either. Indeed in 25 years of working (admittedly in the same industry) in both the public sector and the private sector (in the latter for medium sized consultancies, huge multi-national companies and also as a sole trader), I've never experienced an employer or a customer, or felt any expectation being placed on my shoulders, to respond to an email or take a call outside of normal office hours. Certainly I've never felt at any risk of being fired, not promoted etc. for not doing so.

Conversely, increasingly I am finding that despite all the 'doom and gloom' talk about the economy, people being afraid of losing their jobs etc., there's a sense of apathy amongst many other individuals I come across in my line of work, with people taking excessive time to reply to emails, provide documentation etc, all without any explanation. It doesn't directly affect me, as I'm usually the 'middleman' so the client who is paying both myself and those other individuals sees that I'm doing what I can but also sees that another individual/company isn't pulling their weight.

For example I work on behalf of some very large multinational companies and on Tuesday of this week I both spoke to and then emailed another individual (who is a Director or a medium sized company) whom that company is seeking to urgently do some work on their behalf. Today, 72 hours later and without any acknowledgement or response to my previous email, I covered my own backside by emailing that individual again (copying in the client) seeking confirmation that they'd received my email and again stressing the urgency of the matter. No response.

It's that kind of behaviour I don't get, you're approached by a big multinational company offering you/your company the chance to get involved in a project which could lead to lots more work, you don't say that you're too busy or that you're sorry for the delay and will respond on Monday (which would take a minute of your time), you don't have an out-of-office email on, you simply don't respond to either the initial email and the chasing email 3 days later. And then you wonder why the client has gone elsewhere and neither the client nor myself would ever come to you again.